Medical device delivery

ABSTRACT

A stent delivery system includes a core member and a coupling assembly rotatably coupled to the core member distal segment. The coupling assembly includes first and second plates and first and second spacers. The first plate is rotatably coupled to the core member and includes an outer surface having three or more projections separated by recesses. The first spacer is coupled to the core member and disposed between the first plate and a proximal restraint. The second plate is rotatably coupled to the core member and includes an outer surface having three or more projections separated by recesses. The second spacer is coupled to the core member and disposed between the first plate and the second plate. A stent extends along the core member distal segment such that an inner surface of the stent is engaged by one or more projections of the first plate or the second plate.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/951,890, filed Apr. 12, 2018, the disclosure of which is incorporatedherein by reference in its entirety.

BACKGROUND

Walls of the vasculature, particularly arterial walls, may develop areasof pathological dilatation called aneurysms that often have thin, weakwalls that are prone to rupturing. Aneurysms are generally caused byweakening of the vessel wall due to disease, injury, or a congenitalabnormality. Aneurysms occur in different parts of the body, and themost common are abdominal aortic aneurysms and cerebral (e.g., brain)aneurysms in the neurovasculature. When the weakened wall of an aneurysmruptures, it can result in death, especially if it is a cerebralaneurysm that ruptures.

Aneurysms are generally treated by excluding or at least partiallyisolating the weakened part of the vessel from the arterial circulation.For example, conventional aneurysm treatments include: (i) surgicalclipping, where a metal clip is secured around the base of the aneurysm;(ii) packing the aneurysm with small, flexible wire coils (micro-coils);(iii) using embolic materials to “fill” an aneurysm; (iv) usingdetachable balloons or coils to occlude the parent vessel that suppliesthe aneurysm; and (v) intravascular stenting.

Intravascular stents are well known in the medical arts for thetreatment of vascular stenoses or aneurysms. Stents are prostheses thatexpand radially or otherwise within a vessel or lumen to support thevessel from collapsing. Methods for delivering these intravascularstents are also well known.

Conventional methods of introducing a compressed stent into a vessel andpositioning it within an area of stenosis or an aneurysm includepercutaneously advancing a distal portion of a guiding catheter throughthe vascular system of a patient until the distal portion is proximatethe stenosis or aneurysm. A second, inner catheter and a guidewirewithin the inner catheter are advanced through the distal region of theguiding catheter. The guidewire is then advanced out of the distalregion of the guiding catheter into the vessel until the distal portionof the guidewire carrying the compressed stent is positioned at thepoint of the lesion within the vessel. The compressed stent is thenreleased and expanded so that it supports the vessel at the point of thelesion.

SUMMARY

The present technology is illustrated, for example, according to variousaspects described below. Various examples of aspects of the presenttechnology are described as numbered clauses (1, 2, 3, etc.) forconvenience. These are provided as examples and do not limit the presenttechnology. It is noted that any of the dependent clauses may becombined in any combination, and placed into a respective independentclause, e.g., Clause 1 or Clause 23. The other clauses can be presentedin a similar manner.

Clause 1. A stent delivery system, comprising:

a core member configured for advancement within a corporeal lumen;

a stent extending along the core member, the stent characterized by apore length; and

a coupling assembly positioned about the core member, the couplingassembly comprising:

a first plate rotatably coupled to the core member, the first plateincluding an outer surface having three or more projections engaging thestent; and

a second plate rotatably coupled to the core member, the second plateincluding an outer surface having three or more projections engaging thestent;

wherein the projections of the first plate are spaced longitudinallyfrom the projections of the second plate by a first longitudinaldistance that is slightly less than a whole number multiple of the porelength.

Clause 2. The system of any Clause 1, wherein, in a deliveryconfiguration, the projections of the first plate are engaged with poresof the stent at a first longitudinal position, and wherein theprojections of the second plate are engaged with pores of the stent at asecond longitudinal position, and wherein the first longitudinalposition and the second longitudinal position spaced apart by the firstlongitudinal distance.

Clause 3. The system of any one of Clauses 1-2, wherein the firstlongitudinal distance is less than two pore lengths.

Clause 4. The system of any one of Clauses 1-3, wherein a projection ofthe first plate engages a first pore of the stent, a projection of thesecond plate engages a second pore of the stent, and wherein the firstpore and the second pore are longitudinally adjacent.

Clause 5. The system of any one of Clauses 1-4, wherein the projectionsof the first plate engage the stent at a position less than five porelengths away from a proximal end of the stent.

Clause 6. The system of any one of Clauses 1-5, wherein the projectionsof the first plate engage the stent at a position less than three porelengths away from a proximal end of the stent.

Clause 7. The system of any one of Clauses 1-7, wherein the first plateis configured to tilt with respect to a longitudinal axis of the coremember.

Clause 8. The system of Clause 7, wherein the first plate is configuredto tilt up to 30 degrees with respect to the longitudinal axis of thecore member.

Clause 9. The system of any one of Clauses 7-8, wherein the first plateis configured to tilt up to 20 degrees with respect to the longitudinalaxis of the core member.

Clause 10. The system of any one of Clauses 7-9, wherein the first plateis configured to tilt up to 10 degrees with respect to the longitudinalaxis of the core member.

Clause 11. The system of any one of Clauses 1-11, wherein the secondplate is configured to tilt with respect to a longitudinal axis of thecore member.

Clause 12. The system of any Clause 11, wherein the second plate isconfigured to tilt up to 30 degrees with respect to the longitudinalaxis of the core member.

Clause 13. The system of any one of Clauses 11-12, wherein the secondplate is configured to tilt up to 20 degrees with respect to thelongitudinal axis of the core member.

Clause 14. The system of any one of Clauses 11-13, wherein the secondplate is configured to tilt up to 10 degrees with respect to thelongitudinal axis of the core member.

Clause 15. The system of any one of Clauses 1-14, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 50% of the pore length.

Clause 16. The system of any one of Clauses 1-15, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 40% of the pore length.

Clause 17. The system of any one of Clauses 1-16, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 30% of the pore length.

Clause 18. The system of any one of Clauses 1-17, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 20% of the pore length.

Clause 19. The system of any one of Clauses 1-18, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 10% of the pore length.

Clause 20. The system of any one of Clauses 1-19, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 5% of the pore length.

Clause 21. The system of any one of Clauses 1-20, wherein the couplingassembly further comprises a spacer between the first plate and thesecond plate, and the spacer maintains the projections of the firstplate and the second plate at the first longitudinal distance when thecore member is in a straight orientation and the first plate and thesecond plate abut the spacer.

Clause 22. The system of any one of Clauses 1-21, wherein theprojections of the first plate and the second plate engage the stent byprojecting into pores of the stent.

Clause 23. The system of any one of Clauses 1-22, wherein the porelength of the stent is that attained when the outer diameter of thestent is equal to the inner diameter of a catheter that contains thestent and the coupling assembly and maintains engagement of the firstand second plates and the stent.

Clause 24. The system of any one of Clauses 1-23, wherein:

the stent is a braided stent comprising braided filaments;

a projection of the first plate projects into a first pore of the stent;

a projection of the second plate projects into a second pore of thestent;

the first and second pores are longitudinally adjacent and separated bya filament crossing located longitudinally between the first pore andthe second pore;

the projection of the first plate is longitudinally offset from a centerof the first pore, in a direction toward the filament crossing; and

the projection of the second plate is longitudinally offset from acenter of the second pore, in a direction toward the filament crossingand the projection of the first plate.

Clause 25. The system of any one of Clauses 1-24, further comprising aproximal restraint carried by the core member, wherein the couplingassembly is positioned distal of the proximal restraint.

Clause 26. A stent delivery system, comprising:

a core member;

a stent extending along the core member, the stent comprising aplurality of pores and being characterized by a pore length; and

a coupling assembly carried by the core member; the coupling assemblycomprising:

a first stent engagement member rotatably coupled to the core member,the first stent engagement member including projections engaging a firstplurality of pores of the stent;

a second stent engagement member rotatably coupled to the core member,the second stent engagement member including projections engaging asecond plurality of pores of the stent,

wherein the projections of the first stent engagement member are spacedlongitudinally from the projections of the second stent engagementmember by a first longitudinal distance that is slightly less than awhole number multiple of the pore length.

Clause 27. The system of Clause 26, wherein the first plurality of poresand the second plurality of pores are longitudinally adjacent along alength of the stent.

Clause 28. The system of any one of Clauses 26-27, wherein the firstplurality of pores are less than five pore lengths away from a proximalend of the stent.

Clause 29. The system of any one of Clauses 26-28, wherein the firstplurality of pores are less than three pore lengths away from a proximalend of the stent.

Clause 30. The system of any one of Clauses 26-29, wherein the firstengagement member is configured to tilt with respect to a longitudinalaxis of the core member.

Clause 31. The system of Clause 30, wherein the first engagement memberis configured to tilt up to 30 degrees with respect to the longitudinalaxis of the core member.

Clause 32. The system of any one of Clauses 30-31, wherein the firstengagement member is configured to tilt up to 20 degrees with respect tothe longitudinal axis of the core member.

Clause 33. The system of any one of Clauses 30-32, wherein the firstengagement member is configured to tilt up to 10 degrees with respect tothe longitudinal axis of the core member.

Clause 34. The system of any one of Clauses 26-33, wherein the secondengagement member is configured to tilt with respect to a longitudinalaxis of the core member.

Clause 35. The system of Clause 34, wherein the second engagement memberis configured to up to 30 degrees with respect to the longitudinal axisof the core member.

Clause 36. The system of any one of Clauses 34-35, wherein the secondengagement member is configured to tilt up to 20 degrees with respect tothe longitudinal axis of the core member.

Clause 37. The system of any one of Clauses 34-36, wherein the secondengagement member is configured to tilt up to 10 degrees with respect tothe longitudinal axis of the core member.

Clause 38. The system of any one of Clauses 26-37, wherein the firststent engagement member and the second stent engagement member arespaced apart by less than two pore lengths.

Clause 39. The system of any one of Clauses 26-38, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 50% of the pore length.

Clause 40. The system of any one of Clauses 26-39, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 40% of the pore length.

Clause 41. The system of any one of Clauses 26-40, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 30% of the pore length.

Clause 42. The system of any one of Clauses 26-41, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 20% of the pore length.

Clause 43. The system of any one of Clauses 26-42, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 10% of the pore length.

Clause 44. The system of any one of Clauses 26-43, wherein the firstlongitudinal distance is less than a whole number multiple of the porelength by a decrement that is equal to 1% to 5% of the pore length.

Clause 45. The system of any one of Clauses 26-44, wherein the couplingassembly further comprises a spacer between the first engagement memberand the second engagement member, and the spacer maintains theprojections of the first engagement member and the second engagementmember at the first longitudinal distance when the core member is in astraight orientation and the first engagement member and the secondengagement member abut the spacer.

Clause 46. The system of any one of Clauses 26-45, wherein theprojections of the first engagement member and the second engagementmember engage the stent by projecting into pores of the stent.

Clause 47. The system of any one of Clauses 26-46, wherein the porelength of the stent is that attained when the outer diameter of thestent is equal to the inner diameter of a catheter that contains thestent and the coupling assembly and maintains engagement of the firstand second engagement members and the stent.

Clause 48. The system of any one of Clauses 26-47, wherein:

the stent is a braided stent comprising braided filaments;

a projection of the first engagement member projects into a first poreof the stent;

a projection of the second engagement member projects into a second poreof the stent;

the first and second pores are longitudinally adjacent and separated bya filament crossing located longitudinally between the first pore andthe second pore;

the projection of the first engagement member is longitudinally offsetfrom a center of the first pore, in a direction toward the filamentcrossing; and

the projection of the second engagement member is longitudinally offsetfrom a center of the second pore, in a direction toward the filamentcrossing and the projection of the first engagement member.

Clause 49. The system of any one of Clauses 26-48, further comprising aproximal restraint carried by the core member, wherein the couplingassembly is positioned distal of the proximal restraint.

Clause 50. A method of advancing a stent within a catheter, the methodcomprising:

moving a core member distally within a lumen of the catheter, the coremember carrying a coupling assembly engaged with at least a portion ofthe stent, the coupling assembly including:

a first stent engagement member rotatably carried by the core member andcomprising projections engaged with the stent; and

a second stent engagement member rotatably carried by the core memberand comprising projections engaged with the stent;

wherein the stent is characterized by a pore length; and

wherein the projections of the first stent engagement member are spacedlongitudinally from the projections of the second stent engagementmember;

by moving the core member distally, causing the stent to move distallywithin the catheter lumen with the first engagement member moving nomore than a first lag distance relative to the stent before initiatingdistal movement of the stent;

wherein the first lag distance is no more than 40% of the pore length.

Clause 51. The method of Clause 50, wherein, after distally advancingthe core member such that a portion of the stent is permitted to extendout of the catheter and expand, a proximal portion of the stent remainsengaged with the first stent engagement member.

Clause 52. The method of Clause 51, further comprising proximallyretracting the core member prior to releasing the stent such that thestent is recaptured to within the catheter lumen.

Clause 53. The method of Clause 52, wherein by proximally retracting thecore member, the first stent engagement member pulls the stentproximally within the catheter lumen.

Clause 54. The method of any one of Clauses 52-53, wherein the portionof the stent expanded prior to recapture is at least 50% of the lengthof the stent.

Clause 55. The method of any one of Clauses 52-54, wherein the portionof the stent expanded prior to recapture is at least 75% of the lengthof the stent.

Clause 56. The method of any one of Clauses 52-55, wherein the portionof the stent expanded prior to recapture is at least 90% of the lengthof the stent.

Clause 57. The method of any one of Clauses 52-56, wherein the movingcomprises causing the stent to rotate with respect to the core member.

Clause 58. The method of any one of Clauses 52-57, further comprising byproximally retracting the core member, causing the stent to moveproximally within the catheter lumen with the first engagement membermoving no more than a second lag distance relative to the stent beforeinitiating proximal movement of the stent, wherein the second lagdistance is no more than 40% of the pore length.

Clause 59. The method of any one of Clauses 50-58, wherein theprojections of the first stent engagement member are spacedlongitudinally from the projections of the second stent engagementmember by a first longitudinal distance that is slightly less than awhole number multiple of the pore length.

Clause 60. The method of any one of Clauses 50-59, wherein the first lagdistance is no more than 33% of the pore length.

Clause 61. The method of any one of Clauses 50-60, wherein the first lagdistance is no more than 25% of the pore length.

Clause 62. The method of any one of Clauses 50-61, wherein the first lagdistance is no more than 20% of the pore length.

Clause 63. The method of any one of Clauses 50-62, wherein the first lagdistance is no more than 15% of the pore length.

Clause 64. The method of any one of Clauses 50-63, wherein the first lagdistance is no more than 10% of the pore length.

Clause 65. The method of any one of Clauses 50-64, wherein the first lagdistance is no more than 5% of the pore length.

Clause 66. A stent delivery system, comprising:

a core member configured for advancement within a corporeal lumen;

a stent engagement member coupled to the core member, the engagementmember including:

a proximal end face;

a distal end face;

a side surface extending between the proximal end face and the distalend face, the side surface comprising three or more projectionsseparated by recesses, wherein the projections are unevenly spaced apartfrom one another along the side surface; and

an aperture extending through the proximal end face and second endfaces, the core member extending through the aperture such that theengagement member can rotate about the core member; and

a stent extending along the core member and over the engagement member.

Clause 67. The stent delivery system of Clause 66, wherein theprojections are spaced apart such that each projection is substantiallyaligned with a pore of the stent when the stent is engaged with theengagement member.

Clause 68. The stent delivery system of any one of Clauses 66-17,wherein the stent comprises a braided stent having 48, 54, or 64 wires.

Clause 69. The stent delivery system of any one of Clauses 66-68,wherein the stent comprises a number of pores around its circumferenceat a given longitudinal position along the stent, and wherein the numberof pores is not evenly divisible by the number of projections of theengagement member.

Clause 70. The stent delivery system of Clause 69, wherein the stentcomprises 32 pores at a first longitudinal position along the stent, andwherein the stent engagement member has 3, 5, 6, or 7 projections.

Clause 71. The stent delivery system of any one of Clauses 69-70,wherein the stent comprises 24 pores at a first longitudinal positionalong the stent, and wherein the stent engagement member has 5, 7, or 9projections.

Clause 72. The stent delivery system of any one of Clauses 69-71,wherein the stent comprises 27 pores at a first longitudinal positionalong the stent, and wherein the stent engagement member has 4,5,6,7, or8 projections.

Clause 73. The stent delivery system of any one of Clauses 66-72,wherein the recesses each comprise a concave portion having a radius ofcurvature, and wherein the radius of curvature of the concave portionsvaries among the plurality of recesses.

Clause 74. The stent delivery system of any one of Clauses 66-73,wherein the recesses each comprise a concave portion having a surfacearea, and wherein the surface area of the concave portions varies amongthe plurality of recesses.

Clause 75. The stent delivery system of any one of Clauses 66-74,wherein the recesses each have an angular size, and the recesses vary inangular size.

Clause 76. The stent delivery system of any one of Clauses 66-75,wherein the engagement member comprises a first edge formed at theintersection of the proximal end face and the side surface, and a secondedge formed at the intersection of the distal end face and the sidesurface, and wherein the first edge and the second edge are rounded.

Clause 77. The stent delivery system of any one of Clauses 66-76,wherein the projections each comprise a radially outermost contactregion configured to engage the stent.

Clause 78. The stent delivery system of Clause 77, wherein each contactregion includes:

a central portion;

a first shoulder portion extending from the central portion towards afirst adjacent recess; and

a second shoulder portion extending from the central portion towards asecond adjacent recess.

Clause 79. The stent delivery system of Clause 78, wherein the centralportion comprises a substantially planar outer surface.

Clause 80. The stent delivery system of any one of Clauses 66-79,wherein the projections each comprise a radially outermost contactregion configured to interlock with the stent.

Clause 81. The stent delivery system of any one of Clauses 66-80,wherein the projections each comprise a radially outermost contactregion configured to project into one or more pores of the stent.

Clause 82. The stent delivery system of any one of Clauses 66-81,further comprising a catheter having an inner surface and a lumenthrough which the core member extends, wherein at least a portion of thestent is radially positioned between the engagement member side surfaceand the catheter inner surface.

Clause 83. The stent delivery system of any one of Clauses 66-82,wherein the engagement member has a thickness of between about 50-100microns.

Clause 84. The stent delivery system of any one of Clauses 66-83,wherein the number of protrusions of is between three and six.

Clause 85. The stent delivery system of any one of Clauses 66-84,wherein the stent engagement member comprises a rigid plate.

Clause 86. The stent delivery system of any one of Clauses 66-85,wherein the stent engagement member comprises a sprocket.

Clause 87. The stent delivery system of any one of Clauses 66-86,wherein a radially largest dimension of the stent engagement member isat least five times greater than a thickness of the stent engagementmember.

Clause 88. The stent delivery system of any one of Clauses 66-87,wherein the aperture is configured such that the engagement member cantilt with respect to a longitudinal axis of the core member.

Clause 89. The stent delivery system of any Clause 88, wherein theengagement member can tilt up to 30 degrees with respect to thelongitudinal axis of the core member.

Clause 90. The stent delivery system of any one of Clauses 88-89,wherein the engagement member can tilt up to 20 degrees with respect tothe longitudinal axis of the core member.

Clause 91. The stent delivery system of any one of Clauses 88-90,wherein the engagement member can tilt up to 10 degrees with respect tothe longitudinal axis of the core member.

Clause 92. A stent engagement member for a stent delivery system, theengagement member comprising:

a first end face;

a second end face opposite the first end face;

a side surface extending between the proximal end face and the distalend face, the side surface comprising three or more projectionsseparated by recesses, wherein the projections are unevenly spaced apartfrom one another along the side surface; and

a central opening extending through the proximal end face and second endfaces, the opening configured to receive a core member therethrough.

Clause 93. The stent engagement member of Clause 92, wherein therecesses each comprise a concave portion having a radius of curvature,and wherein the radius of curvature of the concave portions varies amongthe plurality of recesses.

Clause 94. The stent delivery system of any one of Clauses 92-93,wherein the recesses each have an angular size, and the recesses vary inangular size.

Clause 95. The stent engagement member of any one of Clauses 92-94,wherein the recesses each comprise a concave portion having a surfacearea, and wherein the surface area of the concave portions varies amongthe plurality of recesses.

Clause 96. The engagement member system of any one of Clauses 92-95,wherein the engagement member comprises a first edge between theproximal end face and the side surface, and a second edge between thedistal end face and the side surface, and wherein the first edge and thesecond edge are rounded.

Clause 97. The stent engagement member of any one of Clauses 92-96,wherein the projections each comprise a radially outermost contactregion, wherein each contact region includes:

a central portion;

a first shoulder portion extending from the central portion towards afirst adjacent recess; and

a second shoulder portion extending from the central portion towards asecond adjacent recess.

Clause 98. The stent engagement member of Clause 97, wherein the centralportion comprises a generally flat outer surface.

Clause 99. The stent engagement member of any one of Clauses 92-98,wherein the engagement member has a thickness of between about 50-100microns.

Clause 100. The stent engagement member of any one of Clauses 92-99,wherein the number of protrusions of is between three and six.

Clause 101. The stent engagement member of any one of Clauses 92-100,wherein the stent engagement member comprises a rigid plate.

Clause 102. The stent engagement member of any one of Clauses 92-101,wherein the stent engagement member comprises a sprocket.

Clause 103. The stent engagement member of any one of Clauses 92-102,wherein a radially largest dimension of the stent engagement member isat least five times greater than a thickness of the stent engagementmember.

Clause 104. The stent engagement member of any one of Clauses 92-103,wherein the aperture is configured such that the engagement member cantilt with respect to a longitudinal axis of the core member.

Clause 105. A method of advancing a stent delivery assembly through acatheter, the method comprising:

moving a core member distally within a lumen of the catheter, the coremember carrying an engagement member engaged with at least a portion ofa stent, the engagement member including:

a proximal end face, a distal end face, and a side surface extendingbetween the proximal end face and the distal end face, the side surfacecomprising three or more projections separated by recesses, wherein theprojections are unevenly spaced apart from one another along the sidesurface, and wherein the projections are in contact with an innersurface of the stent; and

an aperture extending through the proximal end face and second endfaces, the core member extending through the aperture;

by moving the core member, pulling the stent distally within thecatheter lumen; and

distally advancing the core member such that a portion of the stentcarried by the core member is permitted to extend out of the catheterand expand.

Clause 106. The method of any Clause 105, wherein, after distallyadvancing the core member such that a portion of the stent is permittedto extend out of the catheter and expand, a proximal portion of thestent remains engaged with the stent engagement member.

Clause 107. The method of any one of Clauses 105-106, further comprisingproximally retracting the core member prior to releasing the stent suchthat the stent is recaptured to within the catheter lumen.

Clause 108. The method of Clause 107, wherein by proximally retractingthe core member, the stet engagement member pulls the stent proximallywithin the catheter lumen.

Clause 109. The method of Clause 108, wherein the portion of the stentexpanded prior to recapture is at least 50% of the length of the stent.

Clause 110. The method of any one of Clauses 108-19, wherein the portionof the stent expanded prior to recapture is at least 75% of the lengthof the stent.

Clause 111. The method of any one of Clauses 108-110, wherein theportion of the stent expanded prior to recapture is at least 90% of thelength of the stent.

Clause 112. The method of any one of Clauses 108-111, wherein the movingcomprises causing the stent to rotate with respect to the core member.

Clause 113. A stent delivery system comprising:

a core member configured for advancement within a corporeal lumen;

a coupling assembly positioned about the core member, the couplingassembly comprising:

a first plate rotatably positioned about the core member, the firstplate including an outer surface having three or more projectionsseparated by recesses;

a pushing element positioned on the core member proximal of the firstplate, the pushing element having a distal-facing engagement surface;and

a stent extending along the core member such that the stent is engagedby one or more projections of the first plate, the stent having aproximal edge;

wherein the distal-facing engagement surface of the pushing elementabuts the proximal edge of the stent.

Clause 114. The system of any Clause 113, wherein the pushing element isconfigured to transmit distally directed force to the stent but notproximally directed force.

Clause 115. The system of any one of Clauses 113-114, wherein thecoupling assembly is configured so that the first plate transmitsproximally directed force to the stent but little or no distallydirected force.

Clause 116. The system of any one of Clauses 113-115, wherein thecoupling assembly further comprises a rigid first spacer situatedbetween the first plate and the pushing element.

Clause 117. The system of Clause 116, wherein the first spacer comprisesa solid tube of metal or rigid polymer.

Clause 118. The system of Clause 117, wherein the first spacer lacksflexibility-enhancing cuts.

Clause 119. The system of any one of Clauses 113-118, wherein the firstspacer comprises a proximal end face, a distal end face, and an outersurface extending between the proximal end face and the distal end facealong a longitudinal axis, and wherein the proximal end face and thedistal end face are each substantially orthogonal to the longitudinalaxis of the first spacer.

Clause 120. The system of any one of Clauses 113-119, wherein the firstspacer comprises a flattened proximal end face configured to abutagainst the pushing element.

Clause 121. The system of any one of Clauses 113-120, wherein the stentforms a plurality of openings and the projections of the first plateengage the stent by extending into the openings.

Clause 122. The system of any one of Clauses 113-121, wherein thecoupling assembly further comprises a second plate rotatably positionedabout the core member, the second plate including an outer surfacehaving three or more projections separated by recesses, and wherein oneor more of the projections of the second plate engages the stent viaopenings formed in the stent.

Clause 123. The system of any one of Clauses 113-122, further comprisinga sheath or catheter, wherein the core member, coupling assembly andstent are located within the sheath or catheter.

Clause 124. The system of any one of Clauses 113-123, wherein thepushing element comprises a proximal restraining member.

Clause 125. A medical device delivery system, comprising:

a core member;

a coupling assembly carried by the core member, the coupling assemblycomprising:

a first device engagement member rotatably coupled to the core member,the first device engagement member including an outer surface havingprojections separated by recesses; and

a pushing element positioned on the core member proximal of the firstdevice engagement member, the pushing element having a distal-facingengagement surface.

Clause 126. The system of Clause 125, further comprising:

a medical device extending along the core member such that the medicaldevice is engaged by one or more projections of the first plate;

wherein the medical device has a proximal edge;

wherein the distal-facing engagement surface of the pushing elementabuts the proximal edge of the medical device.

Clause 127. The system of Clause 126, wherein the pushing element isconfigured to transmit distally directed force to the medical device butnot proximally directed force.

Clause 128. The system of any one of Clauses 126-127, wherein thecoupling assembly is configured so that the first device engagementmember transmits proximally directed force to the medical device butlittle or no distally directed force.

Clause 129. The system of any one of Clauses 125-128, wherein thecoupling assembly further comprises a rigid first spacer situatedbetween the first device engagement member and the pushing element.

Clause 130. The system of Clause 129, wherein the first spacer comprisesa solid tube of metal or rigid polymer.

Clause 131. The system of Clause 130, wherein the first spacer lacksflexibility-enhancing cuts.

Clause 132. The system of any one of Clauses 126-131, wherein themedical device forms a plurality of openings and the projections of thefirst device engagement member engage the medical device by extendinginto the openings.

Clause 133. The system of Clause 132, wherein the coupling assemblyfurther comprises a second device engagement member rotatably positionedabout the core member, the second device engagement member including anouter surface having three or more projections separated by recesses,and wherein one or more of the projections of the second deviceengagement member engages the medical device via openings formed in themedical device.

Clause 134. The system of any one of Clauses 126-133, further comprisinga sheath or catheter, wherein the core member, coupling assembly andmedical device are located within the sheath or catheter.

Clause 135. The system of any one of Clauses 125-134, wherein the firstdevice engagement member takes the form of a plate or sprocket.

Clause 136. A method of delivering a tubular medical device through acatheter, the method comprising:

manipulating a delivery system comprising a core member and a couplingassembly, the coupling assembly comprising:

a first device engagement member including an outer surface havingprojections separated by recesses, the projections engaging the medicaldevice via openings in the medical device; and

a pushing element located on the core member, proximal of the firstdevice engagement member; and

moving the medical device distally by transmitting distally-directedforce to the medical device via the pushing element, and nodistally-directed force to the medical device via the first deviceengagement member.

Clause 137. The method of Clause 136, further comprising moving themedical device proximally by transmitting proximally-directed force tothe stent via the first device engagement member, and noproximally-directed force to the stent via the pushing element.

Clause 138. The method of Clause 137, wherein moving the medical deviceproximally comprises resheathing the medical device.

Clause 139. The method of any one of Clauses 137-138, wherein moving themedical device distally comprises partially expanding the medical devicefrom the end of a catheter or sheath, and moving the medical deviceproximally comprises resheathing the medical device into the catheter orsheath.

Clause 140. The method of any one of Clauses 136-39, wherein thecoupling assembly further comprises a first spacer located on the coremember between the first device engagement member and the pushingelement.

Clause 141. The method of Clause 140, further comprising maintainingengagement between the medical device and the pushing element via thefirst spacer.

Clause 142. The method of any one of Clauses 136-141, wherein themedical device comprises a stent.

Clause 143. The method of any one of Clauses 136-142, wherein the firstdevice engagement member takes the form of a plate or sprocket.

Clause 144. A stent delivery system comprising:

a core member configured for advancement within a corporeal lumen;

a coupling assembly positioned about the core member, the couplingassembly comprising:

a first plate rotatably positioned about the core member, the firstplate including an outer surface having three or more projectionsseparated by recesses;

a coil spacer positioned about the core member proximal of and adjacentto the first plate; and

a stent extending along the core member such that the stent is engagedby one or more projections of the first plate and is thereby distallyadvanceable via the core member.

Clause 145. The system of Clause 144, wherein the coil spacer comprisesa zero-pitch coil.

Clause 146. The system of any one of Clauses 144-145, wherein the coilspacer is axially substantially incompressible.

Clause 147. The system of any one of Clauses 144-146, wherein the coilspacer is rotatably positioned about the core member.

Clause 148. The system of any one of Clauses 144-147, wherein the coilspacer comprises a proximal end face, a distal end face, and an outersurface extending between the proximal end face and the distal end facealong a longitudinal axis, and wherein the proximal end face and thedistal end face are each substantially orthogonal to the longitudinalaxis of the coil spacer.

Clause 149. The system of any one of Clauses 144-148, further comprisinga proximal restraint coupled to the core member, and wherein the coilspacer comprises a flattened proximal end face configured to abutagainst the proximal restraint.

Clause 150. The system of any one of Clauses 144-149, wherein the coilspacer comprises a flattened distal end face configured to abut againstthe first plate.

Clause 151. The system of any one of Clauses 144-150, wherein the coilspacer has a length of between about 1-2 mm.

Clause 152. The system of any one of Clauses 144-151, wherein the coilspacer is coated with a lubricious material.

Clause 153. The system of Clause 152, wherein the lubricious materialcomprises PTFE.

Clause 154. The system of any one of Clauses 144-153, wherein an outerdiameter of the coil spacer is less than or equal to a recess diameterof the first plate.

Clause 155. The system of any one of Clauses 144-154, wherein a largestradial dimension of the first plate a is configured to fit within a0.017″, 0.021″ or 0.027″ inner diameter catheter.

Clause 156. The system of any one of Clauses 144-155, wherein the coilspacer comprises a wire having a square or rectangular cross sectionthat is wound into a coil configuration.

Clause 157. The system of any one of Clauses 144-156, wherein the coilspacer comprises a wire that is wound into a coil configuration and thewound wire forms a number of winds, each with flat distal and proximalfaces, wherein the faces of adjacent winds contact each other to enablethe coil spacer to bear longitudinally compressive loads withoutshortening.

Clause 158. The system of any one of Clauses 144-157, further comprisinga proximal restraint coupled to the core member proximal of and adjacentto the coil spacer so as to prevent longitudinal movement of the coilspacer proximal of the proximal restraint.

Clause 159. The system of any one of Clauses 144-158, wherein thecoupling assembly further comprises a second plate rotatably positionedabout the core member, the second plate including an outer surfacehaving three or more projections separated by recesses, and wherein oneor more of the projections of the second plate engages the stent suchthat the stent is distally advanceable via the core member.

Clause 160. The system of Clause 159, further comprising a distalrestraint disposed distal to the second plate, the distal restraintbeing longitudinally fixed with respect to the core member.

Clause 161. The system of any one of Clauses 159-160, wherein a largestradial dimension of the first plate is at least 5 times greater than alargest width dimension of the first plate, and wherein a largest radialdimension of the second plate is at least 5 times greater than a largestwidth dimension of the second plate.

Clause 162. The system of any one of Clauses 159-161, wherein thecoupling assembly further comprises a second spacer positioned about thecore member and disposed between the first plate and the second plate.

Clause 163. The system of Clause 162, wherein the second spacercomprises a second coil spacer.

Clause 164. The system of any one of Clauses 162-163, wherein the secondspacer comprises a solid tubular member.

Clause 165. The system of any one of Clauses 144-164, wherein thecoupling assembly is rotatably positioned about the core member.

Clause 166. A medical device delivery system, comprising:

a core member;

a coupling assembly carried by the core member, the coupling assemblycomprising:

a first device engagement member rotatably coupled to the core member,the first device engagement member including an outer surface havingprojections separated by recesses; and

a coil spacer coupled to the core member and disposed proximal of andadjacent to the first device engagement member.

Clause 167. The system of Clause 166, wherein the coil spacer comprisesa zero-pitch coil.

Clause 168. The system of any one of Clauses 166-167, wherein the coilspacer is axially substantially incompressible.

Clause 169. The system of any one of Clauses 166-168, wherein the coilspacer is rotatably coupled to the core member.

Clause 170. The system of any one of Clauses 166-169, wherein the coilspacer comprises a proximal end face, a distal end face, and an outersurface extending between the proximal end face and the distal end facealong a longitudinal axis, and wherein the proximal end face and thedistal end face are each substantially planar and orthogonal to thelongitudinal axis of the coil spacer.

Clause 171. The system of any one of Clauses 166-170, wherein the coilspacer comprises a flattened proximal end face configured to abutagainst a proximal restraint coupled to the core member.

Clause 172. The system of any one of Clauses 166-171, wherein the coilspacer comprises a flattened distal end face configured to abut againstthe first device engagement member.

Clause 173. The system of any one of Clauses 166-172, wherein the coilspacer has a length of between about 1-2 mm.

Clause 174. The system of any one of Clauses 166-173, wherein the coilspacer is coated with a lubricious material.

Clause 175. The system of Clause 174, wherein the lubricious materialcomprises PTFE.

Clause 176. The system of any one of Clauses 166-175, wherein an outerdiameter of the coil spacer is less than or equal to a recess diameterof the first device engagement member.

Clause 177. The system of any one of Clauses 166-176, wherein the firstdevice engagement member comprises a rigid plate or sprocket.

Clause 178. The system of Clause 177, wherein the coupling assemblyfurther comprises a second device engagement member which comprises arigid plate or sprocket.

Clause 179. The system of any one of Clauses 166-178, wherein the coilspacer comprises a wire having a square or rectangular cross sectionthat is wound into a coil configuration.

Clause 180. The system of any one of Clauses 166-179, wherein the coilspacer comprises a wire that is wound into a coil configuration and thewound wire forms a number of winds, each with flat distal and proximalfaces, wherein the faces of adjacent winds contact each other to enablethe coil spacer to bear longitudinally compressive loads withoutshortening.

Clause 181. The system of any one of Clauses 166-180, further comprisinga proximal restraint coupled to the core member proximal of and adjacentto the coil spacer so as to prevent longitudinal movement of the coilspacer proximal of the proximal restraint.

Clause 182. The system of any one of Clauses 166-181, wherein thecoupling assembly further comprises a second device engagement memberrotatably positioned about the core member, the second device engagementmember including an outer surface having three or more projectionsseparated by recesses.

Clause 183. The system of Clause 182, further comprising a distalrestraint disposed distal to the second device engagement member, thedistal restraint being longitudinally fixed with respect to the coremember.

Clause 184. The system of any one of Clauses 182-183, wherein a largestradial dimension of the first device engagement member is at least 5times greater than a largest width dimension of the first deviceengagement member, and wherein a largest radial dimension of the seconddevice engagement member is at least 5 times greater than a largestwidth dimension of the second device engagement member.

Clause 185. The system of any one of Clauses 182-184, further comprisingan expandable medical device extending along the core member such thatthe medical device is engaged by one or more projections of the firstdevice engagement member and of the second device engagement member, andis thereby distally advanceable via the core member.

Clause 186. The system of Clause 185, wherein the medical devicecomprises a stent.

Clause 187. The system of any one of Clauses 182-186, wherein thecoupling assembly further comprises a second spacer positioned about thecore member and disposed between the first device engagement member andthe second device engagement member.

Clause 188. The system of Clause 187, wherein the second spacercomprises a second coil spacer.

Clause 189. The system of Clause 187, wherein the second spacercomprises a solid tubular member.

Clause 190. The system of any one of Clauses 166-,189 wherein thecoupling assembly is rotatably positioned about the core member.

Clause 191. The system of any one of Clauses 166-190, wherein the coremember is configured for advancement within a corporeal lumen.

Clause 192. A method of advancing a medical device within a catheter,the method comprising:

moving a core member distally within a lumen of the catheter, the coremember carrying a coupling assembly engaged with at least a portion ofthe medical device within the catheter, the coupling assembly including:

a first device engagement member rotatably carried by the core memberand comprising projections engaged with the medical device; and

a coil spacer carried by the core member and positioned proximal of thefirst device engagement member;

by moving the core member distally, causing the medical device to movedistally within the catheter; and

while moving the core member distally, transmitting distally-directedforce from the core member to the first device engagement member and themedical device via the coil spacer, without longitudinal shortening ofthe coil spacer.

Clause 193. The method Clause 192, wherein the medical device comprisesa stent.

Clause 194. The method of any one of Clauses 192-193, wherein moving themedical device distally further comprises causing the medical device toextend out of the catheter and expand.

Clause 195. The method of Clause 194, further comprising proximallyretracting the core member prior to releasing the medical device suchthat the device is recaptured to within the catheter lumen.

Clause 196. The method of any one of Clauses 193-195, wherein, as aresult of proximally retracting the core member, the first deviceengagement member pulls the stent proximally within the catheter lumen.

Clause 197. The method of any one of Clauses 195-196, wherein theportion of the medical device expanded prior to recapture is at least50% of the length of the device.

Clause 198. The method of any one of Clauses 195-197, wherein theportion of the medical device expanded prior to recapture is at least75% of the length of the device.

Clause 199. The method of any one of Clauses 195-198, wherein theportion of the medical device expanded prior to recapture is at least90% of the length of the device.

Clause 200. The method of any one of Clauses 192-199, wherein the movingcomprises causing the medical device to rotate with respect to the coremember.

Clause 201. The method of any one of Clauses 192-200, further comprisingadvancing the core member and coil spacer through a bend in thecatheter, and thereby bending the coil spacer.

Clause 202. The method of Clause 201, wherein bending the coil spacercomprises bending the coil spacer while transmitting distally-directedforce from the core member to the first device engagement member and themedical device via the coil spacer.

Clause 203. The method of any one of Clauses 192-202, wherein thecoupling assembly further comprises a second device engagement memberrotatably carried by the core member and comprising projections engagedwith the medical device.

Clause 204. The method of Clause 203, further comprising while movingthe core member distally, transmitting distally-directed force from thecore member to the second device engagement member and the medicaldevice via the coil spacer.

Clause 205. The method of any one of Clauses 203-204, wherein thecoupling assembly further comprises a second spacer carried by the coremember and located between the first device engagement member and thesecond device engagement member.

Clause 206. The method of any one of Clauses 192-205, wherein themedical device comprises a flow-diverting stent, and further comprisingdeploying the stent from the catheter across an aneurysm to treat theaneurysm via flow diversion therapy.

Additional features and advantages of the present technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the present technology will be realized and attainedby the structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the present technology asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present technology. For ease of reference,throughout this disclosure identical reference numbers may be used toidentify identical or at least generally similar or analogous componentsor features.

FIG. 1 is a schematic illustration of a medical device delivery systemconfigured in accordance with some embodiments.

FIG. 2 is a side, cross-sectional view of a medical device deliverysystem, according to some embodiments.

FIG. 3A is an enlarged perspective view of a coupling assembly havingstent engagement members in accordance with some embodiments.

FIG. 3B is an enlarged perspective view of the coupling assembly of FIG.3A with an overlying stent.

FIGS. 4A and 4B are side and side cross-sectional views, respectively,of a spacer of the coupling assembly shown in FIGS. 2-3B.

FIGS. 5A-5C are side, top, and perspective views, respectively, of anindividual engagement member of the coupling assembly shown in FIGS.2-3B.

FIG. 6A is a schematic cross-sectional view of an engagement member andthe stent of FIG. 3B.

FIG. 6B is an enlarged detail view of a portion of the stent shown inFIG. 3B.

FIG. 7A is a perspective view of another embodiment of an engagementmember.

FIG. 7B is a schematic cross-sectional view of the engagement member ofFIG. 7A engaged with an overlying stent.

FIG. 8A is a perspective view of another embodiment of an engagementmember.

FIG. 8B is a schematic cross-sectional view of the engagement member ofFIG. 8A engaged with an overlying stent.

FIGS. 9A and 9B are side and bottom views, respectively, of anotherembodiment of a stent engagement member.

FIGS. 10A and 10B are side and bottom views, respectively, of anotherembodiment of a stent engagement member.

FIGS. 11A-11C illustrate enlarged detail views of portions of stentengagement members in accordance with different embodiments.

DETAILED DESCRIPTION

Conventional stent engagement members include soft “pads” that rely onfriction fit to secure a stent (such as a braided, knit or woven stent,or a laser-cut stent, or other tubular implant or medical device)against an inner wall of a catheter. Such friction-fit pads may requireseveral different pad diameters to accommodate different stent sidewallthicknesses, which can vary based on the wire size (or combinations ofwire sizes), or the sidewall thickness of the tube stock, used to form agiven stent. That is, within a given catheter size, the internaldiameter of the compressed (braided, knit or woven, or laser-cut) stentcontained in the catheter will vary based on the sizes (diameters) ofthe wires, or the wall thickness of the tube stock, and possibly otherparameters of the stent corresponding to different deployed sizes ortarget vessel sizes. This can require using different pad diameters toaccommodate different stent sizes within a desired range (e.g. about 3.5to 5 millimeters in pad diameter), which necessitates manufacturing thepads of various diameters to very small size tolerances. Embodiments ofthe present technology can allow a single size stent engagement memberto be used with a relatively broad range of stent inner diameters withina given catheter size (e.g. a 0.027″, 0.021″, or 0.017″ inner diametercatheter). For example, a stent engagement member comprising a rigidplate, sprocket or member that has a plurality of projections separatedby recesses can be used to secure a range of different stent sizeswithin a given catheter.

Specific details of several embodiments of the present technology aredescribed herein with reference to FIGS. 1-11C. Although many of theembodiments are described with respect to devices, systems, and methodsfor delivery of stents, tubular implants such as filters, shunts orstent-grafts and other medical devices, other applications and otherembodiments in addition to those described herein are within the scopeof the present technology, and can be employed in any of the embodimentsof systems disclosed herein, in place of a stent as is typicallydisclosed. It should be noted that other embodiments in addition tothose disclosed herein are within the scope of the present technology.Further, embodiments of the present technology can have differentconfigurations, components, and/or procedures than those shown ordescribed herein. Moreover, embodiments of the present technology canhave configurations, components, and/or procedures in addition to thoseshown or described herein and that these and other embodiments may nothave several of the configurations, components, and/or procedures shownor described herein without deviating from the present technology.

As used herein, the terms “distal” and “proximal” define a position ordirection with respect to a clinician or a clinician's control device(e.g., a handle of a delivery catheter). For example, the terms,“distal” and “distally” refer to a position distant from or in adirection away from a clinician or a clinician's control device alongthe length of device. In a related example, the terms “proximal” and“proximally” refer to a position near or in a direction toward aclinician or a clinician's control device along the length of device.The headings provided herein are for convenience only and should not beconstrued as limiting the subject matter disclosed.

Selected Examples of Coupling Assemblies for Medical Device DeliverySystems

FIGS. 1-11C depict embodiments of medical device delivery systems thatmay be used to deliver and/or deploy a medical device, such as but notlimited to a stent, into a hollow anatomical structure such as a bloodvessel. The stent can comprise a braided stent or other form of stentsuch as a woven stent, knit stent, laser-cut stent, roll-up stent, etc.The stent can optionally be configured to act as a “flow diverter”device for treatment of aneurysms, such as those found in blood vesselsincluding arteries in the brain or within the cranium, or in otherlocations in the body such as peripheral arteries. The stent canoptionally be similar to any of the versions or sizes of the PIPELINE™Embolization Device marketed by Medtronic Neurovascular of Irvine,Calif. USA. The stent can alternatively comprise any suitable tubularmedical device and/or other features, as described herein. In someembodiments, the stent can be any one of the stents described in U.S.application Ser. No. 15/892,268, filed Feb. 8, 2018, titled VASCULAREXPANDABLE DEVICES, the entirety of which is hereby incorporated byreference herein and made a part of this specification.

FIG. 1 is a schematic illustration of a medical device delivery system100 configured in accordance with an embodiment of the presenttechnology. The system 100 can comprise an elongate tube or catheter 101which slidably receives a core member or core assembly 103 configured tocarry a stent 105 through the catheter 101. The depicted catheter 101has a proximal region 107 and an opposing distal region 109 which can bepositioned at a treatment site within a patient, an internal lumen 111extending from the proximal region 107 to the distal region 109, and aninner surface 113 defining the lumen 111. At the distal region 109, thecatheter 101 has a distal opening 115 through which the core member 103may be advanced beyond the distal region 109 to expand or deploy thestent 105 within the blood vessel 116. The proximal region 107 mayinclude a catheter hub (not shown). The catheter 101 can define agenerally longitudinal dimension extending between the proximal region107 and the distal region 109. When the delivery system 100 is in use,the longitudinal dimension need not be straight along some or any of itslength.

The core member 103 is configured to extend generally longitudinallythrough the lumen 111 of the catheter 101. The core member 103 cangenerally comprise any member(s) with sufficient flexibility and columnstrength to move the stent 105 or other medical device through thecatheter 101. The core member 103 can therefore comprise a wire, tube(e.g., hypotube), braid, coil, or other suitable member(s), or acombination of wire(s), tube(s), braid(s), coil(s), etc.

The system 100 can also include a coupling assembly 120 or resheathingassembly 120 configured to releasably retain the medical device or stent105 with respect to the core member 103. The coupling assembly 120 canbe configured to engage the stent 105, via mechanical interlock with thepores and filaments of the stent 105, abutment of the proximal end oredge of the stent 105, frictional engagement with the inner wall of thestent 105, or any combination of these modes of action. The couplingassembly 120 can therefore cooperate with the overlying inner surface113 of the catheter 101 to grip and/or abut the stent 105 such that thecoupling assembly 120 can move the stent 105 along and within thecatheter 101, e.g., distal and/or proximal movement of the core member103 relative to the catheter 101 results in a corresponding distaland/or proximal movement of the stent 105 within the catheter lumen 111.

The coupling assembly 120 (or portion(s) thereof) can, in someembodiments, be configured to rotate about the core member 103. In somesuch embodiments, the coupling assembly 120 can comprise a proximalrestraint 119 and a distal restraint 121. The proximal and distalrestraints 119, 121 can be fixed to the core member 103 to prevent orlimit proximal or distal movement of the coupling assembly 120 along thelongitudinal dimension of the core member 103. For example, the proximaland distal restraints 119, 121 can be soldered or fixed with adhesive tothe core wire 103. One or both of the proximal and distal restraints119, 121 can have an outside diameter or other radially outermostdimension that is smaller than the outside diameter or other radiallyoutermost dimension of the overall coupling assembly 120 such that oneor both of the restraints 119, 121 do not contact the inner surface ofthe stent 105 during operation of the system 100. (In some embodiments,as described in further detail below, the proximal restraint 119 can besized to abut the proximal end of the stent 105, and be employed to pushthe stent distally during delivery.) The distal restraint 121 can taperin the distal direction down towards the core member 103. This taperingcan reduce the risk of the distal restraint 121 contacting an innersurface of the stent 105, particularly during navigation of tortuousvasculature, in which the system 100 can assume a highly curvedconfiguration.

The coupling assembly 120 can also include first and second stentengagement members (or device engagement members, or resheathingmembers) 123 a-b (together “engagement members 123”) and first andsecond spacers 125 a-b(together “spacers 125”) disposed about the coremember 103 between the proximal and distal restraints 119, 121. In theillustrated embodiment, from proximal to distal, the elements of thecoupling assembly 120 include the proximal restraint 119, followed bythe first spacer 125 a, the first stent engagement member 123 a, thesecond spacer 125 b, the second stent engagement member 123 b, andfinally the distal restraint 121. In this configuration, the firstspacer 125 a defines the relative positioning of the first engagementmember 123 a and the proximal restraint 119. The second spacer 125 bdefines the relative longitudinal spacing between the first engagementmember 123 a and the second engagement member 123 b.

As described in more detail below, one or both of the spacers 125 cantake the form of a wire coil, a solid tube, or other structural elementthat can be mounted over the core member 103 to longitudinally separateadjacent components of the coupling assembly 120. In some embodiments,one or both of the spacers 125 can be a zero-pitch coil with flattenedends as described in more detail below with respect to FIGS. 4A and 4B.In some embodiments, one or both of the spacers 125 can be a solid tube(e.g., a laser-cut tube) that can be rotatably mounted or non-rotatablyfixed (e.g., soldered) to the core member 103. The spacers 125 can havea radially outermost dimension that is smaller than a radially outermostdimension of the engagement members 123 such that the spacers 125 do notcontact the stent 105 during normal operation of the system 100. Asdescribed in more detail below, the dimensions, construction, andconfiguration of the spacers 125 can be selected to achieve improvedgrip between the coupling assembly 120 and the overlying stent 105.

As described in more detail below with respect to FIGS. 3A, 3B, and5A-11C, one or both of the stent engagement members 123 can be a rigidplate, sprocket or member with a central aperture configured to receivethe core member 103 therethrough. The stent engagement members 123 areconfigured to mechanically interlock with or engage the stent 105 suchthat the stent engagement members 123 restrain the stent 105 from movinglongitudinally with respect to the core member 103.

Although the embodiment illustrated in FIG. 1 includes two stentengagement members 123 and two spacers 125, the number of stentengagement members and spacers can vary. In at least one embodiment, thecoupling assembly 120 includes only a single stent engagement memberwithout any spacers. In other embodiments, the number of stentengagement members can vary, for example two, three, four, five, six, ormore stent engagement members separated by spacers.

In the embodiment of the coupling assembly 120 depicted in FIG. 1 , theproximal restraint 119 is configured to abut the proximal end orproximal edge of the stent 105. In this arrangement the proximalrestraint 119 can be used to move (e.g., push) the stent 105 distallythrough the catheter 101 in response to a distal push force applied tothe core member 103. Such a proximal restraint 119 can have a diameterthat is slightly smaller than the inner diameter of the catheter 101,leaving a small circumferential or radial gap between the outer edge ofthe proximal restraint 119 and the inner wall of the catheter 101. Inaddition, the length of the proximal spacer 125 a can be sized so thatthe proximal edge of the stent 105 abuts the distal face of the proximalspacer 119.

When the proximal restraint 119 is configured to push the stent 105distally, the proximal restraint accordingly transmits some, most or allof the distal longitudinal (push) force to the stent 105, wholly orpartially in place of the stent engagement member(s) 123. In such aconfiguration, the stent engagement members 123 can transmit little orno push force to the stent 105 while the stent 105 is delivered distallyalong the length of the catheter. Advantageously, this reduces oreliminates the tendency of the stent engagement member(s) 123 to distortthe pores of the stent 105 with which the engagement members areengaged, when the engagement members are employed to transmit force toand move the stent 105 within the catheter 101. Use of the proximalrestraint 119 to move the stent 105 in this manner can also reduce oreliminate longitudinal movement of the stent 105 relative to the coremember 103 that sometimes accompanies the pore distortion describedabove. In most cases, the vast majority of the travel of the stent 105within the catheter 101 is in the distal or “push” direction duringdelivery to the treatment location, in contrast to the relatively shorttravel involved in resheathing the stent 105, in the proximal or “pull”direction. Therefore, configuring the proximal restraint 119 to transmitmost or all of the push force to the stent 105 can significantly reduceor substantially eliminate such distortion and/or relative longitudinalmovement of the stent.

The coupling assembly 120 of FIG. 1 can therefore employ the proximalrestraint 119 as a pushing element to transmit at least some, or most orall, distally-directed push force to the stent 105 during delivery. Insuch a coupling assembly 120, the stent engagement member(s) 123 do nottransmit any distally-directed push force to the stent 105 duringdelivery (or transmit only a small portion of such force, or do so onlyintermittently). The stent engagement member(s) 123 can transmitproximally-directed pull force to the stent 105 during retraction orresheathing, and the proximal restraint 119 can transmit noproximally-directed pull force to the stent (or it may do sooccasionally or intermittently, for example when a portion of the stent105 becomes trapped between the outer edge of the proximal restraint 119and the inner wall of the catheter 101).

In some embodiments of the coupling assembly 120 of FIG. 1 , the firstspacer 125 a can be a rigid tube. Such a rigid tube can comprise a solid(e.g., lacking flexibility-enhancing cuts such as spiral cuts orperiodic arcuate cuts) tube of rigid material, e.g. a metal or rigidpolymer. The use of a rigid tube as the first spacer 125 a tends toreduce or eliminate lateral bending of the delivery system 100 aroundthe junction of the proximal restraint 119 and the first spacer 125 a asthe delivery system is advanced through a tortuous path. A lack ofbending in this area can be advantageous when the proximal restraint 119is employed as a pushing element, to transmit distally-directed pushforces to the stent 105 during delivery. When bending occurs, the distalface of the proximal restraint 119 may become poorly engaged with theproximal end of the stent 105, for example engaged only along part ofthe circumference of the stent. This can lead to concentration of pushforce on only a small part of the stent, and/or slippage of the stentinto the radial gap between the outer edge of the proximal restraint andthe inner wall of the catheter 101. Any of these failure modes canadversely affect the function of the delivery system, damage the stent,or both.

In some embodiments, the stent engagement member(s) 123 are employed forboth distal and proximal movement of the stent 105 with respect to thecatheter 101. The engagement member(s) 123 transmit distally-directedforce to the stent 105 to move it distally within the catheter 101during delivery, and proximally-directed force to the stent 105 to moveit proximally into the catheter 101 during resheathing. In suchembodiments, the proximal restraint 119 can be made with a relativelysmall outer diameter, and/or be positioned sufficiently proximal of theproximal end of the stent 105, to prevent the proximal restraint 119from transmitting distally-directed push forces to the stent 105 duringdelivery.

In operation, the stent 105 can be moved distally or proximally withinthe catheter 101 via the core member 103 and the coupling assembly 120.To move the stent 105 out of the catheter 101, either the core member103 is moved distally while the catheter 101 is held stationary or thecore member 103 is held stationary while the catheter 101 is withdrawnproximally. When the core member 103 is moved distally, the distal faceof the proximal restraint 119 bears against the proximal end or edge ofthe stent 105 and causes the stent to be advanced distally, andultimately out of the distal region 109 of the catheter 101. (Inembodiments wherein the stent engagement member(s) 123 are employed totransmit pushing force to the stent 105, the mechanical engagement orinterlock between the stent engagement members 123 and the stent 105, inresponse to the application of a distally-directed force to the coremember 103, causes the stent 105 to move distally through and out of thecatheter 101.) Conversely, to resheath or otherwise move the stent 105into the catheter 101, the relative movement between the core member 103and the catheter 101 is reversed compared to moving the stent 105 out ofthe catheter such that the proximal region of the distal restraint 121bears against the distal region of the second spacer 125 b and therebycauses the spacers 125 and the stent engagement members 123 to beretracted relative to the catheter 101. The mechanical engagementbetween the stent engagement members 123 and the stent 105 accordinglyholds the stent 105 with respect to the core member 103 such thatproximal movement of the stent 105 relative to the catheter 101 enablesre-sheathing of the stent 105 back into the distal region 109 of thecatheter 101. This is useful when the stent 105 has been partiallydeployed and a portion of the stent 105 remains disposed between atleast one of the stent engagement members 123 (e.g. the first stentengagement member 123 a) and the inner surface 113 of the catheter 101because the stent 105 can be withdrawn back into the distal opening 115of the catheter 101 by moving the core member 103 proximally relative tothe catheter 101 (and/or moving the catheter 101 distally relative tothe core member 103). Resheathing in this manner remains possible untilthe stent engagement members 123 and/or catheter 101 have been moved toa point where the first stent engagement member 123 a is beyond thedistal opening 115 of the catheter 101 and the stent 105 is releasedfrom between the first stent engagement member 123 a and the catheter101.

The stent engagement members 123 and the spacers 125 (or any of theengagement members or spacers disclosed herein) can be fixed to the coremember 103 so as to be immovable relative to the core member 103, in alongitudinal/sliding manner and/or in a radial/rotational manner.Alternatively, the spacers 125 and/or the stent engagement members 123can be coupled to (e.g., mounted on) the core member 103 so that thespacers 125 and/or the stent engagement members 123 can rotate about thelongitudinal axis of the core member 103, and/or move or slidelongitudinally along the core member 103. In such embodiments, thespacers 125 and/or the stent engagement members 123 can each have aninner lumen or aperture that receives the core member 103 therein suchthat the spacers 125 and/or the stent engagement members 123 can slideand/or rotate relative to the core member 103. Additionally, in suchembodiments, the proximal and distal restraints 119, 121 can be spacedapart along the core member 103 by a longitudinal distance that isslightly greater than the combined length of the spacers 125 and thestent engagement members 123, so as to leave one or more longitudinalgaps between the first and second spacers 125 a-b, respectively, and theproximal and distal restraints 119, 121. When present, the longitudinalgap(s) allow the spacers 125 and the stent engagement members 123 toslide longitudinally along the core member 103 between the restraints119, 121. The longitudinal range of motion of the spacers 125 and thestent engagement members 123 between the restraints 119, 121 isapproximately equal to the total combined length of the longitudinalgap(s), if any.

Instead of or in addition to the longitudinal gap(s), the couplingassembly 120 can include radial gaps between the outer surface of thecore member 103 and the inner surface of the spacers 125 and the stentengagement members 123. Such radial gaps can be formed when the spacers125 and/or the stent engagement members 123 are constructed with holesthat are somewhat larger than the outer diameter of the correspondingportion of the core member 103. When present, the radial gaps allow thespacers 125 and/or the stent engagement members 123 to rotate about thelongitudinal axis of the core member 103 between the restraints 119,121. The presence of longitudinal gaps of at least a minimal size oneither side of the spacers 125 and the stent engagement members 123 canalso facilitate the rotatability of the spacers 125 and the stentengagement members 123.

In some embodiments, the stent engagement members 123 can be mountedonto the core member 103 to permit not only rotational movement but alsoa degree of tilting of the engagement members 123 with respect to alongitudinal axis of the core member 103. For example, the holes in thestent engagement members 123 can be larger than the outer diameter ofthe corresponding portion of the core member 103, thereby permittingboth rotational movement and tilting with respect to the core member103. “Tilting” as used herein means that the long axis of the stentengagement member 123 (i.e., an axis extending along the longestdimension of the stent engagement member 123, substantially parallel tothe proximal-facing and distal-facing end faces of the stent engagementmember 123) is non-orthogonal to a longitudinal axis of the core member103. For example, in one tilted configuration, the long axis of thefirst stent engagement member 123 a can intersect the core member 103 atapproximately 85 degrees, indicating 5 degrees of tilt. Depending on thedimensions of the stent engagement members 123 and the core member 103,the degree of tilting permitted can vary. In some embodiments, one orboth of the stent engagement members 123 can tilt with respect to thecore member 103 by 30 degrees or less, 20 degrees or less, 10 degrees orless, or 5 degrees or less. In some embodiments, one or both of thestent engagement members 123 can tilt with respect to the core member byat least 5 degrees, by at least 10 degrees, by at least 20 degrees, ormore.

By permitting one or both of the stent engagement members 123 to tiltwith respect to the core member 103, the coupling assembly 120 canbetter navigate tortuous anatomy in which the delivery system 100assumes highly curved states. Additionally, tilting of the stentengagement members 123 can facilitate resheathability of the overlyingstent 105 from a partially deployed state. For example, a stent 105 canbe in a partially deployed state when a portion of the stent 105 hasbeen moved distally beyond a distal end 113 of the catheter 101 suchthat the stent 105 has been released from the second stent engagementmember 123 b yet the stent 105 remains engaged with the first stentengagement member 123 a. From this partially deployed state, the stent105 can be resheathed or recaptured by distally advancing the catheter101 with respect to the coupling assembly 120 (or, alternatively, byproximally retracting the core member 103 and coupling assembly 120 withrespect to the catheter 101). During this movement, as the stent 105moves proximally with respect to the catheter 101, the stent 105 beginsto collapse along its length until it assumes an outer diametercorresponding to the inner diameter of the catheter 101 and engages thesecond stent engagement member 123 b. With continued distal movement ofthe catheter with respect to the coupling assembly 120, the second stentengagement member 123 b is eventually received within the lumen 111 ofthe catheter 101, with the stent 105 interlocked with the stentengagement member 123 b and held in that relationship by the catheter.When the second stent engagement member 123 b initially contacts thedistal end 113 of the catheter 101, there is some risk that theproximal-facing end face of the second stent engagement member 123 bwill abut the distal end 113 of the catheter 101, thereby inhibiting thesecond stent engagement member 123 b from being retracted into the lumen111 of the catheter 101. By allowing the second stent engagement member123 b to tilt with respect to the core member 103, when theproximal-facing end face of the second stent engagement member 123 babuts a distal end of the catheter 101, the second stent engagementmember 123 b can tilt to permit at least a portion of the second stentengagement member 223 b to easily enter the lumen 111 of the catheter101. Once at least a portion of the second stent engagement member 123 bis positioned within the lumen 111, the coupling assembly 120 cancontinue to be retracted until the second stent engagement member 123 bis fully received within the lumen 111, and the stent 105 can be fullyresheathed or recaptured.

FIG. 2 illustrates a side cross-sectional view of another embodiment ofa medical device delivery system 200 configured in accordance with anembodiment of the present technology. The delivery system 200 can beconfigured to carry a stent (or other vascular implant or device) 205thereon to be advanced through a surrounding catheter to a target sitein a patient, similar to the operation described above with respect toFIG. 1 . (The surrounding catheter is omitted in FIG. 2 for clarity).The delivery system 200 can be advanced distally with respect to adistal end of the catheter to expand or deploy the stent 205 at thetarget site.

The delivery system 200 can be used with any number of catheters. Forexample, the catheter can optionally comprise any of the various lengthsof the MARKSMAN™ catheter available from Medtronic Neurovascular ofIrvine, Calif. USA. The catheter can optionally comprise a microcatheterhaving an inner diameter of about 0.030 inches or less, and/or an outerdiameter of 3 French or less near the distal region. Instead of or inaddition to these specifications, the catheter can comprise amicrocatheter which is configured to percutaneously access the internalcarotid artery, or another location within the neurovasculature distalof the internal carotid artery.

The delivery system 200 can comprise a core member or core assembly 202configured to extend generally longitudinally through the lumen of acatheter. The core member 202 can have a proximal region 204 and adistal region 206, which can optionally include a tip coil 208. The coremember 202 can also comprise an intermediate portion 210 located betweenthe proximal region 204 and the distal region 206. The intermediateportion 210 is the portion of the core member 202 onto or over which thestent 205 extends when the core member 202 is in the pre-deploymentconfiguration as shown in FIG. 2 .

The core member 202 can generally comprise any member(s) with sufficientflexibility and column strength to move a stent or other medical devicethrough a surrounding catheter. The core member 202 can thereforecomprise a wire, tube (e.g., hypotube), braid, coil, or other suitablemember(s), or a combination of wire(s), tube(s), braid(s), coil(s), etc.The embodiment of the core member 202 depicted in FIG. 2 is ofmulti-member construction, comprising a wire 212 with a tube 214surrounding the wire 212 along at least a portion of its length. Anouter layer 218, which can comprise a layer of lubricious material suchas PTFE (polytetrafluoroethylene or TEFLON™) or other lubriciouspolymers, can cover some or all of the tube 214 and/or wire 212. Thewire 212 may taper or vary in diameter along some or all of its length.The wire 212 may include one or more fluorosafe markers (not shown), andsuch marker(s) can be located on a portion of the wire 212 that is notcovered by the outer layer 218 (e.g., proximal of the outer layer 218).This portion of the wire 212 marked by the marker(s), and/or proximal ofany outer layer 218, can comprise a bare metal outer surface.

The core member 202 can further comprise a proximal coupling assembly220 and/or a distal interface assembly 222 that can interconnect thestent 205 with the core member 202. The proximal coupling assembly 220can comprise one or more stent engagement members 223 a-b (together“engagement members 223”) that are configured to mechanically engage orinterlock with the stent 205. In this manner, the proximal couplingassembly 220 cooperates with an overlying inner surface of a surroundingcatheter (not shown) to grip the stent 205 such that the proximalcoupling assembly 220 can move the stent 205 along and within thecatheter, e.g., as the user pushes the core member 202 distally and/orpulls the core member proximally relative to the catheter, resulting ina corresponding distal and/or proximal movement of the stent 205 withinthe catheter lumen.

The proximal coupling assembly 220 can, in some embodiments, be similarto any of the versions or embodiments of the coupling assembly 120described above with respect to FIG. 1 . For example, the proximalcoupling assembly 220 can include proximal and distal restraints 219,221 that are fixed to the core member 202 (e.g., to the wire 212 thereofin the depicted embodiment) so as to be immovable relative to the coremember 202, either in a longitudinal/sliding manner or aradial/rotational manner. The proximal coupling assembly 220 can alsoinclude a plurality of stent engagement members 223 separated by spacers225 a-b (together “spacers 225”). The stent engagement members 223 andspacers 225 can be coupled to (e.g., mounted on) the core member 202 sothat the proximal coupling assembly 220 can rotate about thelongitudinal axis of the core member 202 (e.g., of the intermediateportion 210), and/or move or slide longitudinally along the core member202. In some embodiments, the proximal restraint 219 comprises asubstantially cylindrical body with an outer diameter that is greaterthan or equal to an outer diameter of the first spacer 225 a. The distalrestraint 221 can taper in the distal direction down towards the coremember 202. This tapering can reduce the risk of the distal restraint221 contacting an inner surface of the overlying stent 205, particularlyduring navigation of tortuous vasculature, in which the system 200 canassume a highly curved configuration. In some embodiments, the distalrestraint 221 can have an outside diameter or other radially outermostdimension that is smaller than the outside diameter or other radiallyoutermost dimension of the overall proximal coupling assembly 220, sothat distal restraint 221 will tend not to contact the inner surface ofthe overlying stent 205.

In the proximal coupling assembly 220 shown in FIG. 2 , the stent 205can be moved distally or proximally within an overlying catheter (notshown) via the proximal coupling assembly 220. In some embodiments, thestent 205 can be resheathed via the proximal coupling assembly 220 afterpartial deployment of the stent 205 from a distal opening of thecatheter, in a manner similar to that described above with respect tothe coupling assembly 120 in FIG. 1 .

The proximal coupling assembly 220 can be configured and function in amanner similar to the embodiment of the coupling assembly 120 depictedin FIG. 1 . Specifically, the proximal restraint 219 can be made tofunction as a pushing element by appropriately sizing the outer diameterof the proximal restraint 219 and the length of the first spacer 225 a,such that the distal face of the proximal restraint 219 abuts theproximal end or edge of the stent 105. When the proximal couplingelement 220 is so arranged, the proximal restraint 219 can transmit atleast some, or most or all, distally-directed push force to the stent205 during delivery, and the stent engagement member(s) 223 do nottransmit any distally-directed push force to the stent 205 duringdelivery (or transmit only a small portion of such force, or do so onlyintermittently). The stent engagement member(s) 223 can transmitproximally-directed pull force to the stent 205 during retraction orresheathing, and the proximal restraint 219 can transmit noproximally-directed pull force to the stent (or it may do sooccasionally or intermittently, for example when a portion of the stent205 becomes trapped between the outer edge of the proximal restraint 219and the inner wall of the catheter). Again similarly to the couplingassembly 120 shown in FIG. 1 , the first spacer 225 a can optionallytake the form of a solid tube when the proximal coupling assembly 220includes a proximal restraint 219 configured as a pushing element.

Although the proximal coupling assembly 220 can be configured in such amanner, with the proximal restraint 219 abutting the stent 205 so thatthe proximal restraint 219 can be used as a pushing element, thecoupling assembly 220 is depicted with a different configuration inFIGS. 2 and 3A-3B. The depicted configuration entails use of the stentengagement members 223 for both distal (delivery) and proximal(resheathing) movement of the stent 205, as described elsewhere herein.

Optionally, the proximal edge of the proximal coupling assembly 220 canbe positioned just distal of the proximal edge of the stent 205 when inthe delivery configuration. In some such embodiments, this enables thestent 205 to be re-sheathed when as little as a few millimeters of thestent remains in the catheter. Therefore, with stents of typical length,resheathability of 75% or more can be provided (i.e. the stent can bere-sheathed when 75% or more of it has been deployed).

With continued reference to FIG. 2 , the distal interface assembly 222can comprise a distal engagement member 224 that can take the form of,for example, a distal device cover or distal stent cover (generically, a“distal cover”). The distal cover 224 can be configured to reducefriction between the stent 205 (e.g., a distal portion thereof) and theinner surface of a surrounding catheter. For example, the distal cover224 can be configured as a lubricious, flexible structure having a freefirst end or section 224 a that can extend over at least a portion ofthe stent 205 and/or intermediate portion 266 of the core member 202,and a fixed second end or section 224 b that can be coupled (directly orindirectly) to the core member 202.

The distal cover 224 can have a first or delivery position,configuration, or orientation in which the distal cover can extendproximally relative to the distal tip 264, or proximally from the secondsection 224 b or its (direct or indirect) attachment to the core member202, and at least partially surround or cover a distal portion of thestent 205. The distal cover 224 can be movable from the first ordelivery orientation to a second or resheathing position, configuration,or orientation (not shown) in which the distal cover can be everted suchthat the first end 224 a of the distal cover is positioned distallyrelative to the second end 224 b of the distal cover 224 to enable theresheathing of the core member 202, either with the stent 205 carriedthereby, or without the stent 205. As shown in FIG. 2 , the firstsection 224 a of the distal cover 224 can originate from the proximalend of the second section 224 b. In another embodiment, the firstsection 224 a can originate from the distal end of the second section224 b.

The distal cover 224 can be manufactured using a lubricious and/orhydrophilic material such as PTFE or Teflon®, but may be made from othersuitable lubricious materials or lubricious polymers. The distal covercan also comprise a radiopaque material which can be blended into themain material (e.g., PTFE) to impart radiopacity. The distal cover 224can have a thickness of between about 0.0005″ and about 0.003″. In someembodiments, the distal cover can be one or more strips of PTFE having athickness of about 0.001″.

The distal cover 224 (e.g., the second end 224 b thereof) can be fixedto the core member 202 (e.g., to the wire 212 or distal tip thereof) soas to be immovable relative to the core member 202, either in alongitudinal/sliding manner or a radial/rotational manner.Alternatively, as depicted in FIG. 2 , the distal cover 224 (e.g., thesecond end 224 b thereof) can be coupled to (e.g., mounted on) the coremember 202 so that the distal cover 224 can rotate about a longitudinalaxis of the core member 202 (e.g., of the wire 212), and/or move orslide longitudinally along the core member. In such embodiments, thesecond end 224 b can have an inner lumen that receives the core member202 therein such that the distal cover 224 can slide and/or rotaterelative to the core member 202. Additionally, in such embodiments, thedistal interface assembly 222 can further comprise a proximal restraint226 that is fixed to the core member 202 and located proximal of the(second end 224 b of the) distal cover 224, and/or a distal restraint228 that is fixed to the core member 202 and located distal of the(second end 224 b of the) distal cover 224. The distal interfaceassembly 222 can comprise a radial gap between the outer surface of thecore member 202 (e.g., of the wire 212) and the inner surface of thesecond end 224 b. Such a radial gap can be formed when the second end224 b is constructed with an inner luminal diameter that is somewhatlarger than the outer diameter of the corresponding portion of the coremember 202. When present, the radial gap allows the distal cover 224and/or second end 224 b to rotate about the longitudinal axis of thecore member 202 between the restraints 226, 228.

In some embodiments, one or both of the proximal and distal restraints226, 228 can have an outside diameter or other radially outermostdimension that is smaller than the (e.g., pre-deployment) outsidediameter or other radially outermost dimension of the distal cover 224,so that one or both of the restraints 226, 228 will tend not to bearagainst or contact the inner surface of the catheter during operation ofthe core member 202. Alternatively, it can be preferable to make theouter diameters of the restraints 226 and 228 larger than the largestradial dimension of the pre-deployment distal cover 224, and/or make theouter diameter of the proximal restraint 226 larger than the outerdiameter of the distal restraint 228. This configuration allows easy andsmooth retrieval of the distal cover 224 and the restraints 226, 228back into the catheter post stent deployment.

In operation, the distal cover 224, and in particular the first section224 a, can generally cover and protect a distal region of the stent 205as the stent 205 is moved distally through a surrounding catheter. Thedistal cover 224 may serve as a bearing or buffer layer that, forexample, inhibits filament ends of the distal region of the stent 205(where the stent comprises a braided stent) from contacting an innersurface of the catheter, which could damage the stent 205 and/orcatheter, or otherwise compromise the structural integrity of the stent205. Since the distal cover 224 may be made of a lubricious material,the distal cover 224 may exhibit a low coefficient of friction thatallows the distal region of the stent to slide axially within thecatheter with relative ease. The coefficient of friction between thedistal cover and the inner surface of the catheter can be between about0.02 and about 0.4. For example, in embodiments in which the distalcover and the catheter are formed from PTFE, the coefficient of frictioncan be about 0.04. Such embodiments can advantageously improve theability of the core member 202 to pass through the catheter, especiallyin tortuous vasculature.

Structures other than the herein-described embodiments of the distalcover 224 may be used in the core member 202 and/or distal interfaceassembly 222 to cover or otherwise interface with the distal region ofthe stent 205. For example, a protective coil or other sleeve having alongitudinally oriented, proximally open lumen may be employed. In otherembodiments, the distal interface assembly 222 can omit the distal cover224, or the distal cover can be replaced with a component similar to theproximal coupling assembly 220. Where the distal cover 224 is employed,it can be connected to the distal tip coil 208 (e.g., by being wrappedaround and enclosing some or all of the winds of the coil 208) or beingadhered to or coupled to the outer surface of the coil by an adhesive ora surrounding shrink tube. The distal cover 224 can be coupled (directlyor indirectly) to other portions of the core member 202, such as thewire 212.

In embodiments of the core member 202 that employ both a rotatableproximal coupling assembly 220 and a rotatable distal cover 224, thestent 205 can be rotatable with respect to the core member 202 about thelongitudinal axis thereof, by virtue of the rotatable connections of theproximal coupling assembly 220 and distal cover 224. In suchembodiments, the stent 205, proximal coupling assembly 220 and distalcover 224 can rotate together in this manner about the core member 202.When the stent 205 can rotate about the core member 202, the core member202 can be advanced more easily through tortuous vessels as the tendencyof the vessels to twist the stent 205 and/or core member 202 is negatedby the rotation of the stent 205, proximal coupling assembly 220, anddistal cover 224 about the core member 202. In addition, the requiredpush force or delivery force is reduced, as the user's input push forceis not diverted into torsion of the stent 205 and/or core member 202.The tendency of a twisted stent 205 and/or core member 202 to untwistsuddenly or “whip” upon exiting tortuosity or deployment of the stent205, and the tendency of a twisted stent to resist expansion upondeployment, are also reduced or eliminated. Further, in some suchembodiments of the core member 202, the user can “steer” the core member202 via the tip coil 208, particularly if the coil 208 is bent at anangle in its unstressed configuration. Such a coil tip can be rotatedabout a longitudinal axis of the system 200 relative to the stent,coupling assembly 220 and/or distal cover 224 by rotating the distalregion 206 of the core member 202. Thus the user can point the coil tip208 in the desired direction of travel of the core member 202, and uponadvancement of the core member the tip will guide the core member in thechosen direction.

FIG. 3A is an enlarged perspective view of the coupling assembly 220 ofthe medical device delivery system 200, and FIG. 3B illustrates thecoupling assembly 220 with an overlying stent 205. The coupling assembly220 includes first and second engagement members 223 a-b mounted overthe core member 202 adjacent to first and second spacers 225 a-b. Theproximal restraint 219 is disposed proximally to the proximal-mostspacer 225 a, and the distal restraint 221 is disposed distally to thedistal-most engagement member 223 b. As shown in FIG. 3B, the first andsecond stent engagement members 223 a and 223 b can interlock with thestent 205, e.g. by projecting into the pores thereof. The engagementmembers 223 can thereby secure the stent 205, in cooperation with anoverlying catheter (not shown).

FIGS. 4A and 4B are side and cross-sectional views, respectively of aspacer configuration which can serve as the first spacer 225 a of thecoupling assembly 220, or as any spacer of any embodiment of thecoupling assemblies or delivery systems disclosed herein. In at leastsome embodiments, the first spacer 225 a includes a wire coil 230defining a central lumen 232 through which the core member 202 extends.The coil 230 can have a proximal end face 234 and an opposing distal endface 236. The end faces 234, 236 can be substantially planar andsubstantially orthogonal to a longitudinal axis of the coil 230. Forexample, in some embodiments the end faces 234, 236 can be ground,polished, or otherwise flattened to provide planar surfaces that aresubstantially orthogonal to a long axis of the spacer 225 a. This canimprove the pushability or column strength of the overall system 200 asthe planar surface increases the contact area between the proximalrestraint 219 and the proximal end face 234, and also increase thecontact area between the distal end face 236 of the spacer 225 a and thefirst stent engagement member 223 a.

In some embodiments, the coil wire 230 is a zero-pitch coil configuredsuch that, in an unconstrained condition, each winding of the coil 230is in direct contact with an adjacent winding of the coil 230. In suchembodiments, the coil 230 can be substantially incompressible along anaxial direction under the forces typically encountered during use of thedelivery system 200. This incompressibility can provide the pushabilityof a solid tube spacer while also permitting the bending flexibility ofa coil. During bending of the coil 230, one or more of the windings ofthe coil 230 may become partially separated from one another toaccommodate the bending movement. In the absence of external forces, thecoil 230 can return to its unconstrained state (i.e., having zeropitch).

With continued reference to FIGS. 4A and 4B, the lumen 232 of the coil230 can define an inner diameter ID that is slightly larger than acorresponding outer diameter of the core member 202. For example, insome embodiments the lumen 232 can have a diameter of approximatelybetween about 0.008″-0.02″, or between about 0.0160″-0.018″, or betweenabout 0.0165″-0.017″. In at least some embodiments, the coil 230 can befree to rotate with respect to the core member 202. In otherembodiments, the coil wire 230 can be rotationally fixed with respect tothe core member 202, for example by attaching all or a portion of thecoil 230 to the core member 202 using solder, adhesive, or otherattachment technique. In some embodiments, the coil 230 can have aradially outermost diameter (OD) that is smaller than a radiallyoutermost diameter of the stent engagement members 223 (FIGS. 3A and 3B)such that the coil 230 does not contact the overlying stent 205 duringnormal operation of the delivery system 200. In some embodiments, theradially outermost diameter OD of the coil 230 can be between about0.008″-0.02″, or between about 0.016″-0.018″, or between about0.0165″-0.017″.

In some embodiments, the wire that forms the coil 230 can have anindividual thickness or strand diameter SD (FIG. 4B) of between about0.0015-0.006″, or approximately 0.005″. The wire forming the coil 230can have a square or rectangular cross-section along its length. Withsuch a square or rectangular cross-section, the wire can form windshaving flat surfaces that face in the distal and proximal directions.Longitudinally adjacent flat surfaces contact each other and the flatnature of the surfaces provides for a stable, non-bending structureunder longitudinally compressive loads. At the same time, the overallcoil configuration of the spacer is flexible and bendable under bendingloads. The longitudinal length L of the spacer 225 can vary according tothe desired positioning between a proximal restraint 219 and the firststent engagement member 223 a (FIGS. 3A and 3B). For example, in someembodiments the longitudinal length L can be between about 0.03″-0.05″,or between about 0.036″-0.042″, or approximately 0.039″. In otherembodiments, as mentioned above, the first spacer 225 a can be a rigidand/or solid tube.

In some embodiments, the second spacer 225 b can be configured similarlyto the first spacer 225 a, i.e., the second spacer 225 b can also be acoil such as a zero-pitch coil rotatably mounted over the core member202. In other embodiments, the second spacer 225 b can be a solidtubular member. The second spacer 225 b can have a substantiallycylindrical outer surface, substantially planar proximal and distal endfaces, and an inner lumen configured to slidably receive the core member202 therethrough. As described in more detail below, the second spacer225 b can also be configured to have a longitudinal length to separatethe first engagement member 223 a and the second engagement member 223 bby a desired amount. For example, in at least some embodiments, thesecond spacer 225 b can have a length such that the first engagementmember 223 a is separated from the second engagement member 223 b byapproximately 1-3 times the pore pitch of the overlying stent 205, forexample in some embodiments approximately equal to the pore length ofthe overlying stent 205.

In some embodiments, the first spacer 225 a and/or the second spacer 225b can be coated with a lubricious material, for example PTFE, parylene,or other coating. The coating can be provided along an outer surface ofthe spacer 225, within an interior lumen (e.g., lumen 232 of the coil230), or both. In some embodiments, the lubricious coating improves therotatability of the spacer 225 with respect to the core member 202 andcan also reduce friction between the spacer 225 and the overlying stent205 or catheter in the event that the spacer 225 contacts thesecomponents during use of the delivery system 200.

FIGS. 5A-5C are side, end, and perspective views, respectively, of astent engagement member 223 of the coupling assembly 220 shown in FIGS.3A and 3B. FIG. 6A is a schematic cross-sectional view of the stentengagement member 223 engaging the stent 205 within an overlyingcatheter 267, and FIG. 6B is an enlarged detail view of a portion of thestent 205. The depicted stent 205 is braided (although other types ofstent, as disclosed elsewhere herein may be used) and includes a mesh263 forming a plurality of pores 265 which are bounded by filaments,wires or struts and separated by points where the filaments, wires orstruts cross (e.g., in the case of a braided or woven device) orintersect (e.g., in the case of a laser-cut device).

Referring to FIGS. 3A, 3B, and 5A-6B together, each of the stentengagement members 223 can have a plate-like or sprocket-likeconfiguration with first and second end faces 251, 253 and a sidesurface 255 extending between the first and second end faces 251, 253.In the assembled delivery system 200, the first and second end faces251, 253 can be oriented and maintained substantially orthogonal to along axis of the core member 202 (or the engagement members can beconfigured to tilt to a desired degree, as discussed elsewhere herein).This can be achieved by configuring the spacers 225 with distal andproximal end faces that are orthogonal to the longitudinal axis of eachspacer 225 (and/or to the core member 202), and/or minimizing the amountof longitudinal movement space (or “play”) among the stent engagementmembers and spacers of the coupling assembly 220. Each stent engagementmember forms a plurality of radially extending projections 257 separatedby recesses 259. In the illustrated embodiment, there are fourprojections 257 separated by four recesses 259. However, in otherembodiments the number of projections can vary, for example two, three,four, five, six, seven, or more projections separated by a correspondingnumber of recesses.

In some embodiments, the projections 257 include rounded edges or convexportions and the recesses 259 include rounded depressions or convexportions. During use of the delivery system 200, the rounded edges canreduce scraping of the projections 257 against the inner wall of anoverlying catheter 267, which reduces generation of particulates anddamage to the catheter 267. When the delivery system 200 is used with abraided stent such as the depicted stent 205, the recesses 259 can besized to accommodate the thickness of braid wire crossings such thateach projection 257 can extend at least partially into a pore 265 of thestent 205 between the adjacent wire crossings and the wire crossingssurrounding the pore 265 can be at least partially received within therecesses 259 of the stent engagement member. In other embodiments, theprojections and/or the recesses can assume other forms, for example withsharper or flatter peaks formed by the projections 257.

Each stent engagement member 223 can include an opening or centralaperture 261 configured to receive the core member 202 therethrough. Theopening of the aperture 261 can be larger than the diameter of the coremember 202 such that the stent engagement members 223 can rotate aboutthe long axis of the core member 202. As noted above, in someembodiments, the aperture 261 can be sufficiently larger than thediameter of the core member 202 to permit a degree of tilting of theengagement members 223 with respect to a longitudinal axis of the coremember 202.

The stent engagement members 223 can be made to have a relatively thinand/or plate-like or sprocket-like configuration. Such a configurationcan facilitate the formation of projections 257 that are small enough tofit inside the pores 265 of the stent 205. Accordingly, the stentengagement members 223 may be characterized by a largest radialdimension or diameter D along the first and second end faces 251, 253,and a thickness T measured along the side surface 255. In someembodiments, the diameter D is at least five times greater than thethickness T. In at least one embodiment, the thickness T is betweenapproximately 25-200 microns, or 50-100 microns, for example,approximately 80 microns.

To effectively push or pull the stent 205 along a surrounding catheter,the stent engagement members 223 can be made to be rigid (e.g.,incompressible by the forces encountered in typical use of the deliverysystem). The rigidity of the stent engagement members 223 can be due totheir material composition, their shape/construction, or both. In someembodiments, the stent engagement members 223 are made of metal (e.g.,stainless steel, Nitinol, etc.) or rigid polymers (e.g., polyimide,PEEK), or both. In some embodiments, even if the stent engagement memberis made of a rigid material, based on structural characteristics thestent engagement member itself may be non-rigid and at least partiallycompressible.

As noted above, the spacers 225 can be substantially cylindrical bodieshaving a smaller outer diameter than a largest outer diameter of thestent engagement members 223. In some embodiments, the spacers 225include a central aperture sized and configured to allow the spacers 225to be rotatably mounted over the core member 202. As mentionedpreviously, the spacers 225 can have end walls that are orthogonal to along axis of the core member 202. These orthogonal end walls can helppreserve the orthogonal orientation of the stent engagement members 223relative to the core member 202 to prevent loss of engagement with stent205. (Alternatively, the engagement members can be configured to tilt toa desired degree, as discussed elsewhere herein.) As described above, insome embodiments one or both of the first and second spacers 225 a and225 b can be a wire coil defining a cylindrical body mounted over thecore member 225 a, for example a zero-pitch coil. In other embodiments,one or both of the first and second spacers 225 a and 225 b can takeother forms, for example a solid cylindrical tube or other elementcoupled to the core member 202.

In some embodiments, the coupling assembly 220 can be configured toengage only a proximal portion (e.g., the proximalmost 5%, theproximalmost 10%, the proximalmost 20%, only a proximal half, etc.) ofthe stent 205. In other embodiments, coupling assembly 220 can engagethe stent 205 along substantially its entire length.

The stent engagement members 223 can mechanically interlock with orengage the stent 205 such that each projection 257 is at least partiallyreceived within one of the pores 265. In some embodiments, the firstengagement member 223 a can engage with a proximal portion of the stent205, for example at a position less than 5 pores or pore lengths awayfrom a proximal end of the stent, or less than 3 pores or pore lengthsaway from the proximal end of the stent 205, etc. The spacers 225 can beconfigured with a length such that the projections 257 of adjacent stentengagement members 223 (e.g., the first stent engagement member 223 aand adjacent second stent engagement member 223 b) are spaced apartlongitudinally by a distance that is substantially equal to the “porelength” (or “pore pitch”) of the stent 205 (defined herein as thelongitudinal distance between the centers of longitudinally adjacent andnon-overlapping pores 265 when the stent is in the compressedconfiguration wherein the outer diameter of the stent is equal to theinner diameter of the catheter) or, in some embodiments, a whole-numbermultiple of the pore length of the stent 205. For example, in someembodiments, the first and second stent engagement members 223 a and 223b are spaced apart by between about 1-3 times the pore length of thestent 205 when the stent is at the inner diameter of the catheter 267.Accordingly, each projection can extend into and engage one of the pores265 of the stent 205.

FIG. 6B is a schematic illustration of a portion of the stent 205, whichincludes a plurality of pores 265 a-265 d. As noted above, projections257 of the stent engagement member 223 can engage individual pores 265of the stent 205. In some embodiments, adjacent stent engagement members223 engage longitudinally adjacent pores 265 of the stent 205. As usedherein, “longitudinally adjacent” means that there is not an interveningpore in the longitudinal direction between the two pores. Longitudinallyadjacent pores, however, can be non-adjacent radially, e.g., a firstpore located at the “twelve o'clock” position on the circumference ofthe stent can be longitudinally adjacent to a second pore located at the“six o'clock” position on the circumference of the stent (or at anypoint on the circumference in between) if, in the longitudinaldirection, there is no intervening pore between the two. For example,referring to FIG. 6B, the first pore 265 a is longitudinally adjacent toeach of the second pore 265 b, the third pore 265 c, and the fourth pore265 d. However, the first pore 265 a is not longitudinally adjacent tothe fifth pore 265 e, because there are intervening pores between thetwo. In other embodiments, adjacent stent engagement members 223 engagepores which are not longitudinally adjacent but are spaced apartlongitudinally by one or more intervening pores, for example the firstpore 265 a and the fifth pore 265 e. Therefore, the first and secondstent engagement members 223 a and 223 b can be spaced apart from oneanother by a longitudinal distance corresponding to the pore pitch ofthe stent 205, or by a longitudinal distance corresponding to a wholenumber multiple of the pore pitch.

In some embodiments, the longitudinal spacing between the first andsecond stent engagement members 223 a and 223 b can be slightly lessthan the pore length (e.g., 50% less, 40% less, 30% less, 20% less, 10%less, or 5% less than the pore length, etc.), or slightly less than awhole number multiple of the pore length (e.g., less by a decrementequal to 50%, 40%, 30%, 20%, 10%, or 5% of a single pore length, etc.).This slightly smaller spacing between the first and second stentengagement members 223 a and 223 b can provide improved grip on thestent 205 by minimizing the longitudinal “play” between the projections257 of the first and second engagement members 223 a and 223 b and thewire crossing(s) or intersection point(s) positioned between theengagement members. As a result, a longitudinal movement of the coremember causes a corresponding longitudinal movement of the stent withminimal delay and high precision. For example, a proximal movement ofthe core member (and/or the engagement member(s) carried thereby) causesa proximal movement of the stent, with the engagement member(s) movingno more than a first lag distance relative to the stent beforeinitiating proximal movement of the stent. The first lag distance can bemore than 40% of the pore length of the stent, or no more than 33%, orno more than 25%, or no more than 20%, or no more than 15%, or no morethan 10%, or no more than 5% of the pore length. Instead of or inaddition to such a first pore length, a distal movement of the coremember (and/or the engagement member(s) carried thereby) causes a distalmovement of the stent, with the engagement member(s) moving no more thana second lag distance relative to the stent before initiating distalmovement of the stent. The second lag distance can be more than 40% ofthe pore length of the stent, or no more than 33%, or no more than 25%,or no more than 20%, or no more than 15%, or no more than 10%, or nomore than 5% of the pore length.

The interaction between the projections 257 and the pores 265 canproduce a mechanical interlock between stent engagement member 223 andthe pores 265. This is in contrast to a conventional compressible padthat resiliently pushes against the stent as a whole, including the wirecrossings. In at least some embodiments, the mechanical interlockprovided by the stent engagement members 223 secures the stent 205without pressing against the wire crossings of the stent 205. In someembodiments, the stent engagement members 223 are configured to secure arange of different stent sizes within a given catheter size (e.g.,within a 0.017″, 0.021″ or 0.027″ catheter (inside diameter)).

The stent engagement members 223 can be made of substantially rigidmaterials, for example metal, biocompatible polymers (e.g., PEEK), orother suitable materials. In some embodiments, the stent engagementmembers 223 can be made of stainless steel and manufactured using lasercutting followed by electropolishing. For example, a plurality ofengagement members can be laser-cut from a sheet of stainless steelhaving the desired thickness (e.g., approximately 100 microns thick).Electropolishing can further reduce the thickness of the resulting stentengagement members, for example from 100 microns to approximately 80microns. In other embodiments, the stent engagement members can bemanufactured using other techniques, for example injection molding,chemical etching, or machining.

Note that various components of the delivery system 200 of FIGS. 2-6 canbe incorporated into the delivery system 100 of FIG. 1 , and vice versa.For example, any of the disclosed embodiments of the coupling assembly220 can be employed as the coupling assembly 120 of the delivery system100. Similarly, any of the embodiments of the stent engagement members223 can be employed as the stent engagement member(s) 123 of thedelivery system 100, and/or any of the embodiments of the spacers 225can be employed as the spacer(s) 125 of the delivery system 100.Although many embodiments discussed herein include two engagementmembers 223, in other embodiments the delivery system 200 can includethree, four, or more engagement members separated from one another byadditional spacers. The spacing of such additional engagement memberscan be regular or irregular. For example, in one embodiment a thirdengagement member can be provided at a position configured to engage adistal region of the overlying stent, while the first and secondengagement members engage only a proximal region of the overlying stent.

Additional Examples of Stent Engagement Members for Coupling Assemblies

In various embodiments, the stent engagement members of the couplingassembly can take additional forms. For example, the number ofprojections, the contours of the projections and recesses, the materialselected, and dimensions can all vary to achieve desired operation ofthe coupling assembly. FIGS. 7A-11C illustrate various alternativeembodiments of stent engagement members. These stent engagement memberscan be incorporated into and combined with the coupling assemblies 120and 220 described above with respect to FIGS. 1-6 . Additionally,aspects of these stent engagement members can be combined and intermixedsuch that features of any one of these stent engagement members (e.g.,the number of protrusions or recesses, etc.) can be combined with thefeatures of any of the other stent engagement members disclosed herein(e.g., the width of the contact region, spacing of the protrusions,etc.). In some embodiments, the individual stent engagement members of agiven coupling assembly can be substantially identical in shape, size,and construction. In other embodiments, however, the properties of theindividual stent engagement members can vary within a single couplingassembly, such as having different sizes, shapes, or materialconstruction. For example, a single coupling assembly can have a firststent engagement member having a given number of protrusions, and asecond stent engagement member having a different number of protrusions.

FIG. 7A illustrates a perspective view of another embodiment of a stentengagement member 723, and FIG. 7B illustrates a cross-sectional view ofthe stent engagement member 723 of FIG. 7A engaged with an overlyingstent 705 disposed within a catheter 767. Embodiments of the engagementmember 723 can be similar to those described above with respect to theengagement member 223, except that the engagement member 723 includesthree projections 757 separated by three recesses 759. The engagementmember 723 engages and mechanically interlocks with an overlying stent705, and the surrounding catheter 767 helps maintain such engagementuntil the interlocked portion of the stent exits the catheter. The stent705 includes a mesh 763 defining a plurality of pores 765 which areseparated by points where the wires, filaments, struts etc. of the mesh763 cross (e.g., in the case of a braided stent) or intersect (e.g., inthe case of a laser-cut stent). The radially extending projections 757can each extend at least partially into a pore 765 of the stent 705between adjacent crossing or intersection points and the crossing orintersection points surrounding the pore 765 can be at least partiallyreceived within the recesses 759 of the stent engagement member 723. Inother embodiments, the projections and/or the recesses can assume otherforms, for example with sharper or flatter peaks formed by theprojections 759. The stent engagement member 723 includes an opening orcentral aperture 761 configured to receive a core member or coreassembly therethrough. The opening of the aperture 761 can be largerthan the diameter of the core member such that the stent engagementmember 763 can rotate about the long axis of the core member. As notedabove, in some embodiments, the aperture 761 can be sufficiently largerthan the diameter of the core member to permit a degree of tilting ofthe engagement member 723 with respect to a longitudinal axis of thecore member.

FIG. 8A illustrates a perspective view of another embodiment of a stentengagement member 823, and FIG. 8B illustrates a cross-sectional view ofthe stent engagement member 823 of FIG. 8A engaged with an overlyingstent 805 disposed within a catheter 867. Embodiments of the engagementmember 823 can be similar to those described above with respect to theengagement members 223 and 723, except that the engagement member 823includes six projections 857 separated by six recesses 859. The stent805 includes a mesh 863 defining a plurality of pores 865 which areseparated by points where the wires, filaments, struts, etc. of the meshcross or intersect. The radially extending projections 857 can eachextend at least partially into a pore 865 of the stent 805 betweenadjacent crossing or intersection points, and the crossing orintersection points surrounding the pore 865 can be at least partiallyreceived within the recesses 859 of the stent engagement member 823. Inother embodiments, the projections and/or the recesses can assume otherforms, for example with sharper or flatter peaks formed by theprojections 859. A central aperture 861 can be configured to receive acore member or core assembly therethrough and can be sized to permit thestent engagement member 823 to rotate and/or tilt with respect to thecore member.

Depending on the particular construction of the overlying stent 705,805, in some embodiments the protrusions 757, 857 of the stentengagement members 723, 823 can be radially evenly spaced around theengagement members. For example, with respect to FIG. 7B, the centerpoint of each protrusion 759 can be separated from the next protrusion759 by 120 degrees. Similarly, as shown in FIG. 8B, the six protrusions857 of the stent engagement member 823 can be radially evenly spacedaround the engagement member 823, such that each protrusion 857 isseparated from an adjacent protrusion 857 by 60 degrees. In braidedstents, the number of strands defines the number of available poresradially aligned along any particular longitudinal location of thestent. For example, FIGS. 7B and 8B illustrate a cross-sectional viewsof 48-wire braided stents 705, 805 engaged with the stent engagementmembers 723 and 823, respectively. The 48-wire stents 705, 805 eachdefines 24 pores 765, 865 around the circumferences of the stents 705,805. In some embodiments, aligning each protrusion 757, 857 with a pore765, 865 improves the strength with which the stent engagement member723, 823 interlocks with the overlying stent 705, 805, as well asoverall mechanical fit and compatibility. Accordingly, it can beadvantageous to align the protrusions 757, 857 with pores 765, 865 ofthe overlying stents 705, 805. Since the stent 705 of FIG. 7B includes24 pores 765, and since the 24 pores can be evenly divided into thirds,the three protrusions 757 of the stent engagement member 723 can beradially evenly spaced while each being aligned with one of the pores765. Similarly, since the stent 805 of FIG. 8B includes 24 pores 865,and since the 24 pores can be evenly divided into sixths, the sixprotrusions 857 of the stent engagement member 823 can be radiallyevenly spaced while each being aligned with one of the pores 865. Inother embodiments, the number of protrusions can be two, four, or eight,and the protrusions can be evenly spaced around the stent engagementmember.

In other embodiments, the number of protrusions of the stent engagementmember and the number and/or location of pores defined by the overlyingstent can be such that even radial spacing of the protrusions would bedisadvantageous. For example, a braided stent with 48 wires (and 24pores) can be used with a stent engagement member that has 5protrusions, in which case these protrusions cannot be evenly spacedaround the engagement member and still each be aligned with pores of thestent. As another example, a braided stent with 54 wires will define 27pores at a particular longitudinal position of the stent. Since the 27pores cannot be evenly divided among four, five, or six protrusions, theprotrusions may instead be unevenly radially spaced. In yet anotherexample, a 64-wire stent will have 32 pores, which cannot be evenlydivided among three, five, or six protrusions. In each of these cases,it can be advantageous to provide a stent engagement member withprotrusions that are unevenly spaced apart from one another around acircumference of the engagement member. Similarly, in the case of alaser-cut stent, the pores may not be evenly radially spaced around thecircumference of the device, and a stent engagement member with unevenlyradially spaced can be useful with such a stent.

FIGS. 9A-10B illustrate two embodiments of such stent engagement memberswith unevenly spaced protrusions. Embodiments of the stent engagementmembers 923, 1023 described herein can be similar to the stentengagement members 123, 223, 723, and 823 described above, except thatat least some embodiments can include unevenly spaced protrusions. FIGS.9A and 9B illustrate side and bottom views, respectively, of the stentengagement member 923, which includes a six protrusions 957 a-fseparated by six recesses 959 a-f. As shown in FIG. 9A, the recesses 959a-f can be shaped and sized differently from one another such that theprotrusions 959 a-f are not evenly spaced around the periphery of theengagement member 923. For example, the space or angular separationbetween the first protrusion 957 a and second protrusion 957 b is lessthan the space or angular separation between the second protrusion 957 band the third protrusion 957 c. In one example, the angle between thefirst protrusion 957 a and the second protrusion 957 b can be 55.8degrees, while the angle between the second protrusion 957 b and thethird protrusion 957 c can be 68.5 degrees. This varied spacing can beachieved, e.g., by varying the structure of the individual recesses 959a-f. For example, each recess 959 a-f can include a concave surfacewhich curves inwardly between adjacent protrusions 959 a-f. Certainrecesses can have a larger surface area and/or a larger radius ofcurvature than other protrusions, thereby extending the radial spacingbetween adjacent protrusions. For example, the second recess 959 b hasboth a greater surface area and a greater radius of curvature than thefirst recess 959 a. This structure results in the spacing between thefirst and second protrusions 957 a and 957 b being smaller than thespacing between the second and third protrusions 957 b and 957 c. In theillustrated embodiment, the first recess 959 a, third recess 959 c,fourth recess 9859 d, and sixth recess 959 d are similarly configured toprovide corresponding radial spacing between adjacent protrusions ofapproximately 55.8 degrees, while the second recess 959 b and the fifthrecess 959 e are similarly configured to provide corresponding radialspacing between adjacent protrusions of approximately 68.5 degrees. Thisprovides radial symmetry about certain axes, while also providing unevenspacing for improved engagement with an overlying stent. Othervariations are possible, in which the particular angles between adjacentprotrusions can be varied within ranges such that each protrusion 957a-f is configured to project into or mechanically interlock with a poreof an overlying stent.

As seen best in FIG. 9B, the engagement member 923 includes opposingfirst and second end faces 951, 953, with a side surface 955 extendingbetween the two. The protrusions 957 a-f and the recesses 959 a-f canall be disposed along the side surface 955. In some embodiments, theedge formed at the intersection of the first end face 951 and the sidesurface 955 and the edge formed at the intersection of the second endface 953 and the side surface 955 can both be rounded. In particular,the edges at the projections 957 a-f can be rounded, since in at leastsome embodiments only these outermost portions of the engagement member923 contact (or otherwise engage with) an overlying stent or catheter.In contrast to embodiments in which there is a sharp edge between thesesurfaces (e.g., approximately a right-angle between two planar andorthogonal surfaces), the rounded edges can reduce scraping against acatheter inner wall, reducing damage and generation of particulatematter when an overlying catheter is moved with respect to theengagement member 923.

FIGS. 10A and 10B illustrate side and bottom views, respectively, ofanother embodiment of a stent engagement member 1023 with fiveprotrusions 1057 a-e that are unevenly spaced apart from one another byfive recesses 1059 a-e. The recesses 1059 a-e can be shaped and sizeddifferently from one another such that the protrusions 1059 a-e are notevenly spaced around the periphery of the engagement member 1023.Rather, angle between the first protrusion 1057 a and second protrusion1057 b, and the angle between the first protrusion and the fifthprotrusion 1057 e, can each be approximately 78.8 degrees. In contrast,the angle between the second protrusion 1057 b and the fourth protrusion1059 b, and the angle between the fourth protrusion 1057 d and the fifthprotrusion 1057 e, can each be approximately 67.7 degrees. Finally, theangle between the third protrusion 1057 c and the fourth protrusion 1057d can be approximately 66.9 degrees. This varied spacing can be achievedby varying the structure of the individual recesses 1059 a-e. Forexample, the first recess 1059 a has both a greater surface area and agreater radius of curvature than the second recess 1059 b, resulting inthe spacing between the first and second protrusions 1057 a and 1057 bbeing greater than the spacing between the second and third protrusions1057 b and 1057 c. Other variations are possible, in which theparticular angles between adjacent protrusions can be varied withinranges such that each protrusion 1057 a-e is configured to project intoor mechanically interlock with a pore of an overlying stent.

As seen best in FIG. 10B, the engagement member 1023 includes opposingfirst and second end faces 1051, 1053, with a side surface 1055extending between the two. The protrusions 1057 a-e and the recesses1059 a-e can all be disposed along the side surface 1055. As discussedabove with reference to FIG. 9B, in some embodiments, the edges formedat the intersection of the first end face 1051 and the side surface 1055and formed at the intersection of the second end face 1053 and the sidesurface 1055 can be rounded to reduce friction and damage to anoverlying catheter or the stent.

FIGS. 11A-11C illustrate enlarged detail views of projections 1157 a-cof stent engagement members in accordance with different embodiments. Asdescribed above with respect to engagement members 123, 223, 723, 823,923, and 1023, engagement members can include a plurality of projectionsseparated by recesses. The projections can form the radially outer-mostcomponents of the stent engagement members, which in use can contact anoverlying stent or otherwise interlock with it, in cooperation with anoverlying catheter inner wall. The projections 1157 a-c each include anoutermost contact region 1169, characterized by a length D, which isconfigured to contact (or otherwise engage with) an overlying stent. Thecontact region 1169 can include a central portion 1171 flanked byopposing shoulder portions 1173 a and 1173 b. The shoulder portions 1173a and 1173 b can extend between the central portion 1171 and opposingextensions 1175 a and 1175 b. The extensions 1175 a and 1175 b extendaway from the contact region 1169 and towards corresponding recesses(not shown) of the stent engagement member. The central portion 1171 canhave a substantially planar outermost surface, which can be coplanarwith the adjacent shoulder portions 1173 a and 1173 b. However, theshoulder portions 1173 a and 1173 b can have curved outer surfaces whichjoint the central portion 1171 and the adjacent extensions 1175 a and1175 b.

Together, the central portion 1171 and shoulder portions 1173 a, 1173 bdefine the length D of the contact region 1169. In certain embodiments,it can be advantageous to increase the overall surface area of thecontact region 1169 by increasing the length D as compared toembodiments in which there is little or no central portion 1171. Amongthe embodiments shown in FIGS. 11A-C, the length D of the contact region1169 is varied such that the length D is greatest in the protrusion 1157a of FIG. 11A, then smaller in the protrusion 1157 b of FIG. 11B, andsmallest in the protrusion 1157 c of FIG. 11C. As a result, theprotrusion 1157 a has the greatest surface area configured to contact anoverlying stent or catheter, followed by protrusion 1157 b which has asmaller surface area configured to contact an overlying stent orcatheter, and finally protrusion 1157 c having a still smaller surfacearea configured to contact an overlying stent or catheter. In variousembodiments, the length D of the contact region 1169 can be betweenabout 0.001″-0.004″, or between about 0.002″-0-0.003″. For example, insome embodiments the contact region 1169 can have a length D of about0.002″, about 0.0025″, or about 0.003″. As will be appreciated, thevarious embodiments of the contact region 1169 can generally comprise aflat or planar central region, and first and second shoulders on eitherside of the central region. The shoulders can be rounded in up to twodirections (radially as seen in FIGS. 11A-11C, and/or axially as seen inFIGS. 9B and 10B).

Conclusion

This disclosure is not intended to be exhaustive or to limit the presenttechnology to the precise forms disclosed herein. Although specificembodiments are disclosed herein for illustrative purposes, variousequivalent modifications are possible without deviating from the presenttechnology, as those of ordinary skill in the relevant art willrecognize. In some cases, well-known structures and functions have notbeen shown and/or described in detail to avoid unnecessarily obscuringthe description of the embodiments of the present technology. Althoughsteps of methods may be presented herein in a particular order, inalternative embodiments the steps may have another suitable order.Similarly, certain aspects of the present technology disclosed in thecontext of particular embodiments can be combined or eliminated in otherembodiments. Furthermore, while advantages associated with certainembodiments may have been disclosed in the context of those embodiments,other embodiments can also exhibit such advantages, and not allembodiments need necessarily exhibit such advantages or other advantagesdisclosed herein to fall within the scope of the present technology.Accordingly, this disclosure and associated technology can encompassother embodiments not expressly shown and/or described herein.

Throughout this disclosure, the singular terms “a,” “an,” and “the”include plural referents unless the context clearly indicates otherwise.Similarly, unless the word “or” is expressly limited to mean only asingle item exclusive from the other items in reference to a list of twoor more items, then the use of “or” in such a list is to be interpretedas including (a) any single item in the list, (b) all of the items inthe list, or (c) any combination of the items in the list. Additionally,the terms “comprising” and the like are used throughout this disclosureto mean including at least the recited feature(s) such that any greaternumber of the same feature(s) and/or one or more additional types offeatures are not precluded. Directional terms, such as “upper,” “lower,”“front,” “back,” “vertical,” and “horizontal,” may be used herein toexpress and clarify the relationship between various elements. It shouldbe understood that such terms do not denote absolute orientation.Reference herein to “one embodiment,” “an embodiment,” or similarformulations means that a particular feature, structure, operation, orcharacteristic described in connection with the embodiment can beincluded in at least one embodiment of the present technology. Thus, theappearances of such phrases or formulations herein are not necessarilyall referring to the same embodiment. Furthermore, various particularfeatures, structures, operations, or characteristics may be combined inany suitable manner in one or more embodiments.

The invention claimed is:
 1. A method of advancing a stent within acatheter, the method comprising: moving a core member distally within alumen of the catheter, the core member carrying a coupling assemblyengaged with at least a portion of the stent, the coupling assemblyincluding: a first stent engagement member rotatably carried by the coremember and comprising projections engaged with the stent; and a secondstent engagement member rotatably carried by the core member andcomprising projections engaged with the stent; wherein the stent ischaracterized by a pore length; and wherein the projections of the firststent engagement member are spaced longitudinally from the projectionsof the second stent engagement member; by moving the core memberdistally, causing the stent to move distally within the catheter lumenwith the first stent engagement member moving no more than a first lagdistance relative to the stent before initiating distal movement of thestent; wherein the first lag distance is no more than 40% of the porelength.
 2. The method of claim 1, wherein the projections of the firststent engagement member are spaced longitudinally from the projectionsof the second stent engagement member by a longitudinal distance that isless than a whole number multiple of the pore length by a decrement thatis equal to between 1% and 50% of the pore length.
 3. The method ofclaim 1, wherein, after distally moving the core member such that aportion of the stent is permitted to extend out of the catheter andexpand, a proximal portion of the stent remains engaged with the firststent engagement member.
 4. The method of claim 3, further comprisingproximally retracting the core member prior to releasing the stent suchthat the stent is recaptured to within the catheter lumen.
 5. The methodof claim 4, wherein by proximally retracting the core member, the firststent engagement member pulls the stent proximally within the catheterlumen.
 6. The method of claim 4, wherein the portion of the stentexpanded prior to recapture is at least 50% of the length of the stent.7. The method of claim 6, wherein the portion of the stent expandedprior to recapture is at least 90% of the length of the stent.
 8. Themethod of claim 1, wherein the first lag distance is no more than 5% ofthe pore length.
 9. The method of claim 1, wherein the moving comprisescausing the stent to rotate with respect to the core member.
 10. Amethod of advancing a stent within a catheter, the method comprising:moving a core member distally within a lumen of the catheter, the coremember carrying an engagement member rotatably positioned about the coremember; wherein the engagement member comprises three or moreprojections engaging the stent such that at least one of the projectionsextends into a pore of the stent; and wherein the stent is characterizedby a pore length; by moving the core member distally, causing the stentto move distally within the catheter lumen with the engagement membermoving no more than a first lag distance relative to the stent beforeinitiating distal movement of the stent; wherein the first lag distanceis no more than 40% of the pore length; and by moving the core memberproximally, causing the stent to move proximally within the catheterlumen with the engagement member moving no more than a second lagdistance relative to the stent before initiating proximal movement ofthe stent; wherein the second lag distance is no more than 40% of thepore length.
 11. The method of claim 10, wherein after moving the coremember distally, a first portion of the stent extends out of thecatheter and radially expands, and a second portion of the stent remainsengaged with the engagement member.
 12. The method of claim 11, whereinafter moving the core member proximally, at least a portion of the firstportion of the stent is retracted into the lumen of the catheter and isradially compressed.
 13. The method of claim 11, wherein a length of thefirst portion is at least 50% of the length of the stent.
 14. The methodof claim 10, wherein the engagement member is a first engagement member,the core member carrying the first engagement member and at least oneadditional engagement member rotatably positioned about the core memberand longitudinally spaced from the first engagement member.
 15. Themethod of claim 10, wherein causing the stent to move distally withinthe catheter lumen comprises the engagement member transmitting adistally directed force to the stent.
 16. The method of claim 10,wherein causing the stent to move proximally within the catheter lumencomprises the engagement member transmitting a proximally directed forceto the stent.